Det for loop i C-sprog bruges til at gentage udsagn eller en del af programmet flere gange. Det bruges ofte til at krydse datastrukturer som arrayet og den linkede liste.
Syntaks for for loop i C
Syntaksen for for loop i c-sprog er angivet nedenfor:
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for(Expression 1; Expression 2; Expression 3){ //code to be executed } Flowchart over for loop i C
C for sløjfeeksempler
Lad os se det enkle program for for loop, der udskriver tabel med 1.
#include int main(){ int i=0; for(i=1;i<=10;i++){ printf('%d
',i); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 5 6 7 8 9 10 </pre> <h3>C Program: Print table for the given number using C for loop</h3> <pre> #include int main(){ int i=1,number=0; printf('Enter a number: '); scanf('%d',&number); for(i=1;i<=10;i++){ printf('%d
',(number*i)); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> Enter a number: 2 2 4 6 8 10 12 14 16 18 20 </pre> <pre> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 </pre> <h3>Properties of Expression 1</h3> <ul> <li>The expression represents the initialization of the loop variable.</li> <li>We can initialize more than one variable in Expression 1.</li> <li>Expression 1 is optional.</li> <li>In C, we can not declare the variables in Expression 1. However, It can be an exception in some compilers.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf('%d ',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf('%d ',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf('%d ',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf('%d %d %d
',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf('%d %d
',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf('%d ',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)></pre></=10;i++){></pre></=10;i++){> C Program: Udskriv tabel for det givne tal ved hjælp af C for loop
#include int main(){ int i=1,number=0; printf('Enter a number: '); scanf('%d',&number); for(i=1;i<=10;i++){ printf(\'%d
\',(number*i)); } return 0; < pre> <p> <strong>Output</strong> </p> <pre> Enter a number: 2 2 4 6 8 10 12 14 16 18 20 </pre> <pre> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 </pre> <h3>Properties of Expression 1</h3> <ul> <li>The expression represents the initialization of the loop variable.</li> <li>We can initialize more than one variable in Expression 1.</li> <li>Expression 1 is optional.</li> <li>In C, we can not declare the variables in Expression 1. However, It can be an exception in some compilers.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf(\'%d \',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)></pre></=10;i++){> Enter a number: 1000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
Egenskaber for udtryk 1
- Udtrykket repræsenterer initialiseringen af loop-variablen.
- Vi kan initialisere mere end én variabel i udtryk 1.
- Udtryk 1 er valgfrit.
- I C kan vi ikke erklære variablerne i udtryk 1. Det kan dog være en undtagelse i nogle compilere.
Eksempel 1
#include int main() { int a,b,c; for(a=0,b=12,c=23;a<2;a++) { printf(\'%d \',a+b+c); } < pre> <p> <strong>Output</strong> </p> <pre> 35 36 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)></pre></2;a++)> Eksempel 2
#include int main() { int i=1; for(;i<5;i++) { printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 1 2 3 4 </pre> <h3>Properties of Expression 2</h3> <ul> <li>Expression 2 is a conditional expression. It checks for a specific condition to be satisfied. If it is not, the loop is terminated.</li> <li>Expression 2 can have more than one condition. However, the loop will iterate until the last condition becomes false. Other conditions will be treated as statements.</li> <li>Expression 2 is optional.</li> <li>Expression 2 can perform the task of expression 1 and expression 3. That is, we can initialize the variable as well as update the loop variable in expression 2 itself.</li> <li>We can pass zero or non-zero value in expression 2. However, in C, any non-zero value is true, and zero is false by default.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)></pre></5;i++)> Egenskaber for udtryk 2
- Udtryk 2 er et betinget udtryk. Den kontrollerer, om en bestemt betingelse er opfyldt. Hvis den ikke er det, afsluttes løkken.
- Udtryk 2 kan have mere end én betingelse. Løkken vil dog iterere, indtil den sidste betingelse bliver falsk. Andre forhold vil blive behandlet som udsagn.
- Udtryk 2 er valgfrit.
- Udtryk 2 kan udføre opgaven med udtryk 1 og udtryk 3. Det vil sige, at vi kan initialisere variablen samt opdatere loop-variablen i selve udtryk 2.
- Vi kan sende nul eller ikke-nul værdi i udtryk 2. Men i C er enhver ikke-nul værdi sand, og nul er falsk som standard.
Eksempel 1
by i uas
#include int main() { int i; for(i=0;i<=4;i++) { printf(\'%d \',i); } < pre> <p> <strong>output</strong> </p> <pre> 0 1 2 3 4 </pre> <p> <strong>Example 2</strong> </p> <pre> #include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\'%d %d %d
\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\'%d %d
\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\'%d \',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)></pre></=4;i++)> Eksempel 2
#include int main() { int i,j,k; for(i=0,j=0,k=0;i<4,k<8,j<10;i++) { printf(\\'%d %d %d
\\',i,j,k); j+="2;" k+="3;" } < pre> <p> <strong>Output</strong> </p> <pre> 0 0 0 1 2 3 2 4 6 3 6 9 4 8 12 </pre> <p> <strong>Example 3</strong> </p> <pre> #include int main() { int i; for(i=0;;i++) { printf('%d',i); } } </pre> <p> <strong>Output</strong> </p> <pre> infinite loop </pre> <h4>Properties of Expression 3 <ul> <li>Expression 3 is used to update the loop variable.</li> <li>We can update more than one variable at the same time.</li> <li>Expression 3 is optional.</li> </ul> <p> <strong>Example 1</strong> </p> <pre> #include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\\'%d %d
\\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)></pre></h4></4,k<8,j<10;i++)> Eksempel 3
#include int main() { int i; for(i=0;;i++) { printf('%d',i); } } Produktion
infinite loop
Udtryksegenskaber 3 - Udtryk 3 bruges til at opdatere loop-variablen.
- Vi kan opdatere mere end én variabel på samme tid.
- Udtryk 3 er valgfrit.
Eksempel 1
i.næste java
#include void main () { int i=0,j=2; for(i = 0;i<5;i++,j=j+2) { printf(\\'%d %d
\\',i,j); } < pre> <p> <strong>Output</strong> <pre> 0 2 1 4 2 6 3 8 4 10 </pre> </p><h3>Loop body</h3> <p>The braces {} are used to define the scope of the loop. However, if the loop contains only one statement, then we don't need to use braces. A loop without a body is possible. The braces work as a block separator, i.e., the value variable declared inside for loop is valid only for that block and not outside. Consider the following example.</p> <pre> #include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)></pre></5;i++,j=j+2)> Løkke krop
Klammerne {} bruges til at definere løkkens omfang. Men hvis løkken kun indeholder et udsagn, behøver vi ikke bruge klammeparenteser. En løkke uden krop er mulig. Klammerne fungerer som en blokadskiller, dvs. værdivariablen, der er erklæret inde for løkke, er kun gyldig for den blok og ikke udenfor. Overvej følgende eksempel.
#include void main () { int i; for(i=0;i<10;i++) { int i="20;" printf(\\'%d \\',i); } < pre> <p> <strong>Output</strong> </p> <pre> 20 20 20 20 20 20 20 20 20 20 </pre> <h3>Infinitive for loop in C</h3> <p>To make a for loop infinite, we need not give any expression in the syntax. Instead of that, we need to provide two semicolons to validate the syntax of the for loop. This will work as an infinite for loop.</p> <pre> #include void main () { for(;;) { printf('welcome to javatpoint'); } } </pre> <p>If you run this program, you will see above statement infinite times.</p> <hr></10;i++)> Infinitiv for loop i C
For at gøre en for-løkke uendelig, behøver vi ikke give noget udtryk i syntaksen. I stedet for det skal vi angive to semikoloner for at validere syntaksen for for-løkken. Dette vil fungere som en uendelig for loop.
#include void main () { for(;;) { printf('welcome to javatpoint'); } } Hvis du kører dette program, vil du se ovenstående erklæring uendelige gange.