Usage of string function in c language

string The function library provides functions for operating strings, including: string comparison functions (strcmp(), strncmp(), strcasecmp()) string copy functions (strcpy(), strncpy()) characters String connection functions (strcat(), strncat()) String search functions (strchr(), strstr()) String conversion functions (strtol(), strtof(), strcpy()) String formatting functions (sprintf() ), sscanf())

Usage of string function in C language

Question: What is the use of string function in C language?

Answer: The string function library provides functions for operating strings, including string comparison, copying, concatenation, search, conversion and formatting, etc.

Detailed description:

String comparison function:

• strcmp(): Compare two strings Equality
• strncmp(): Compares the first n characters of two strings to see if they are equal
• strcasecmp(): Compares two strings case-insensitively

String copy function:

• strcpy(): Copy one string to another string
• strncpy(): Copy a character Copy the first n characters of the string to another string

String concatenation function:

• strcat(): Append a string To another string
• strncat(): Append the first n characters of a string to another string

String search function:

• strchr(): Find the first specified character in the string
• strstr(): Find the first specified substring in the string

String conversion function:

##strtol(): Convert a string to a long integer
• strtof(): Convert a string to float Floating point number
• strcpy(): Convert a string to uppercase or lowercase

##String formatting function:

sprintf(): Format data into a string

• sscanf(): Extract data from a string

Example:

<code class="c">#include <stdio.h>
#include <string.h>

int main() {
    char str1[] = "Hello";
    char str2[] = "World";

    // 比较字符串
    int result = strcmp(str1, str2);
    if (result == 0) {
        printf("字符串相等\n");
    } else if (result < 0) {
        printf("str1 小于 str2\n");
    } else {
        printf("str1 大于 str2\n");
    }

    // 复制字符串
    strcpy(str1, str2);
    printf("str1 现在是 %s\n", str1);

    // 连接字符串
    strcat(str1, "C");
    printf("str1 现在是 %s\n", str1);

    // 搜索字符串
    char *pos = strchr(str1, 'o');
    if (pos != NULL) {
        printf("字符 'o' 在字符串中\n");
    }

    // 转换字符串
    int num = strtol(str2, NULL, 10);
    printf("str2 转换为整数为 %d\n", num);

    return 0;
}</code>

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