C for loop

In this lesson, you will learn about for loops in C, their usage, and examples to better understand the topic.

What are loops in Programming?

A Loop is an Iterative Control Structure that includes several executions of the same lines of code
until a particular condition is fulfilled.” Loops are used as long as a specific requirement is encountered to perform the same block of code repeatedly. The fundamental concept behind a loop is to automate repetitive assignments within a program.

Three distinct loop kinds are supported by C:

For — loops through a code block until the counter reaches a given number.
While — loops through a code block as long as the given condition is true.
Do … while — the code block will be assessed once and then. If the condition is true, the statement will be repeated as long as the condition specified is true.

In this lesson, we will focus on the For loops, and the Next lessons will cover the while and do-while loops.

The for Loop Statement in C

The for loop loops thought a code block until a specific number of iterations is reached. It’s used widely in programming to loop thought lists of objects and Data Structures.

Syntax of for loop in C

for (initialize; condition; increment){
    //code to be processed here
}

“For…{…}” is generally an integer loop block; it is used to set the original value of the counter.
“Condition” means the condition assessed for each execution of C. If it is valid, then execution of the for… The loop is closed. If it assesses false, the execution of the for… The loop goes on. “Increment” is used to increase the counter integer’s original value.

Flow Chart of For Loop

The flowchart below helps you understand the flow for the loop in C.

Note: The loop is used if you understand how often the script should run in advance.

Example of for loops in C

// Print the values from 1 to 5
#include <stdio.h>

int main() {
  int var;
  for (var = 1; var <= 5; ++ var) {
    printf("%d\n", var);
  }
  return 0;
}

Output

Another Example of for loops in C

// Print the Table of 2 from 1 to 10
#include <stdio.h>
int main()
{
  int var, evennumber;
  printf ("C ***For loop*** Example\n");
  printf (" -------For loop ---------\n");
  printf ("The table of %d \n", 2);
  for (var = 1; var <= 10; var++)
    { //executes 10 times and increment
      evennumber = 2 * var;
      printf ("2 * %d is %d \n", var, evennumber);
    }
  return 0;
}

Output

2 * 3 is 6 
2 * 4 is 8 
2 * 5 is 10 
2 * 6 is 12 
2 * 7 is 14 
2 * 8 is 16 
2 * 9 is 18 
2 * 10 is 20

C Nested For Loop Statement

In Programming, you can use a loop inside another loop, which we call loop nesting. A nested for loop is fully executed for one outer loop in the case of an inner or nested loop. If the outer loop is to be executed four times and the inner loop three times, both loops will iterate 12 times ( 4 x 3)

Syntax of Nested loops in C

Example of for Nested Loop in C

// Print Nested For loop
#include <stdio.h>
int main ()
{
  int var, var2;
  printf ("C ***Nested For loop*** Example\n");
  for (var = 1; var <= 4; var++)
    { //executes 4 times and increment
      printf ("Outer Loop %d times \n", var);
      for (var2 = 1; var2 <= 3; var2++)
    { //executes 3 times and increment
      printf ("Inner Loop %d times \n", var2);
    }
      printf ("\n");
    }
  return 0;
}

Output

C ***Nested For loop*** Example
Outer Loop 1 times
Inner Loop 1 times
Inner Loop 2 times
Inner Loop 3 times
Outer Loop 2 times
Inner Loop 1 times
Inner Loop 2 times
Inner Loop 3 times
Outer Loop 3 times
Inner Loop 1 times
Inner Loop 2 times
Inner Loop 3 times
Outer Loop 4 times
Inner Loop 1 times
Inner Loop 2 times
Inner Loop 3 times

In the next lesson, you will learn about another type of loop in C, the while loop.

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