How to count the number of characters in a string in C language?

You can use the strlen function to count the number of characters in a string.

The prototype of the strlen function is as follows:

size_t strlen(const char *str);

In this case, the ‘str’ is the string for counting the number of characters.

Example code:

#include<stdio.h>
#include<string.h>

int main() {
    char str[100];
    printf("请输入一个字符串：");
    scanf("%s", str);
    
    int count = strlen(str);
    printf("字符串中的字符个数为：%d\n", count);
    
    return 0;
}

Run the code, input a string, and the program will print the number of characters in the string.