C Language Zemi

while statement-repeating syntax

You can write iteratively using the while statement.

while (repetition condition) {
  
}

This is a sample to calculate the total with a while statement.

#include <stdint.h>
#include <stdio.h>

int main (void) {
  
  // Find the total with a while statement
  int32_t total = 0;
  int32_t i = 0;
  while (i <10) {
    total + = i;
    i ++;
  }
  
  printf("%d\n", total);
}

The total from 0 to 9 is output.

45 45

The above while statement can be written concisely using for statement.

Use of while statement and for statement properly

How do you use the while statement and the for statement properly?

Sample for which for statement is suitable

Processing that uses indexes such as arrays can be written in a for statement in an easy-to-understand and concise manner. If the index spacing is fixed, such as +1 or +2, the for statement is sufficient.

#include <stdint.h>
#include <stdio.h>

int main (void) {
  
  int32_t nums [3] = {1, 3, 5};
  
  // Find the total with a for statement
  int32_t total = 0;
  for (int32_t i = 0; i <3; i ++) {
    total + = nums [i];
  }
  
  printf("%d\n", total);
}

Sample for which while statement is suitable

If the above does not apply, write using a while statement. This is not an absolute standard, so use it as a rough guide.

For example, while seems to be suitable for the process of finding the terminal character "\ 0" in a string.

#include <stdint.h>
#include <stdio.h>

int main (void) {
  
  // String constant
  const char * string = "abc";
  
  // A pointer to a single character (the beginning of a string constant)
  const char * buf_ptr = string;

  // Repeat until the terminating character "\ 0" appears
  while (* buf_ptr! ='\ 0') {
    
    // * to extract the actual character and output it
    printf("%c\n", * buf_ptr);
    
    // Increment the pointer to advance the character position
    buf_ptr ++;
  }
}