#include <stdio.h>
int main()
{
char s[1000];
int i;
printf("Enter a string: ");
scanf("%s", s);
for(i = 0; s[i] != '\0'; ++i);
printf("Length of string: %d", i);
return 0;
}

Output

Enter a string: Program
Length of string: 7

C program to find the length of a string:

#include <stdio.h>

int main() {
    char str[100];
    int length = 0, i;

    printf("Enter a string:\n");
    gets(str);

    for (i = 0; str[i] != '\0'; i++) {
        length++;
    }

    printf("Length of the string: %d\n", length);

    return 0;
}

Explanation:

• #include <stdio.h> includes the standard input-output header file in our program.
• char str[100]; declares a character array str to store the input string.
• int length = 0, i; declares an integer variable length and a loop variable i.
• The printf() the statement is used to display a message to the user to input a string and the gets() the function is used to input the string.
• The for the loop starting from for (i = 0; str[i] != '\0'; i++) counting the number of characters in the string str until the end of the string is reached.
• The last printf() the statement displays the length of the string.

When we compile and run this program, it will prompt the user to input a string and then find its length. Finally, it will display the length of the string.