How to use tolower in c language

tolower() function converts characters to lowercase, accepts ASCII code values ​​and returns the corresponding lowercase version. This function is often used to convert a string to lowercase. The parameter is the ASCII code value of the string. If the input is an uppercase letter, lowercase is returned. If it is a lowercase letter or non-letter, the original value is returned.

Usage of tolower in C language

tolower() function is used to convert characters in the C standard library Lowercase functions. It accepts an ASCII value of type int as a parameter and returns the lowercase version of the character. If the input is not an ASCII value, the original value is returned.

Syntax:

int tolower(int c);

Parameters:

• c: The character to be converted ASCII code value.

Return value:

• If the input is an ASCII uppercase letter, its lowercase version is returned.
• If the input is ASCII lowercase letters or not letters, the original value will be returned.

Usage:

tolower() function is often used to convert strings to lowercase. Here is an example:

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

int main() {
    char str[] = "THIS IS A STRING";

    // 将字符串转换为小写
    for (int i = 0; i < strlen(str); i++) {
        str[i] = tolower(str[i]);
    }

    printf("小写字符串：%s\n", str);

    return 0;
}

Output:

<code>小写字符串：this is a string</code>

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