Determine the length of a message. Uses well-known idiom for determining end of line. source: http://knking.com/books/c2/programs/length2.c

length2.c

// Determine the length of a message

#include <stdio.h>

int main(void) 
{
    int len = 0;
    
    printf("Enter a message: ");
    while (getchar() != '\n')
        len++;
    printf("Your message was %d character(s) long.\n", len);
    
    return 0;
}