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C语言字符串处理

C语言字符串处理

• strlen()：计算字符串长度

  • 语法格式：size_t strlen(const char *s);
  • 示例：int len = strlen("Hello"); // len = 5

• strcpy()：复制字符串

  • 语法格式：char *strcpy(char *dest, const char *src);
  • 示例：strcpy(dest, "Hello");

• strcmp()：比较两个字符串

  • 语法格式：int strcmp(const char *s1, const char *s2);
  • 示例：int result = strcmp("apple", "banana"); // result < 0

• strcat()：连接两个字符串

  • 语法格式：char *strcat(char *dest, const char *src);
  • 示例：strcat(dest, " World");

• sprintf()：格式化输出到字符串

  • 语法格式：int sprintf(char *str, const char *format, ...);
  • 示例：sprintf(str, "Age: %d", 25);

• strncpy()：复制指定长度的字符串

  • 语法格式：char *strncpy(char *dest, const char *src, size_t n);
  • 示例：strncpy(dest, src, 10);

• strstr()：查找子字符串

  • 语法格式：char *strstr(const char *haystack, const char *needle);
  • 示例：char *pos = strstr("Hello World", "World");

• strchr()：查找字符在字符串中的位置

  • 语法格式：char *strchr(const char *s, int c);
  • 示例：char *pos = strchr("Hello", 'l');

字符串处理示例

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

int main() {
    char str1[50] = "Hello";
    char str2[50] = "World";
    char result[100];
    int length, compare;
    
    // 计算字符串长度
    length = strlen(str1);
    printf("Length of str1: %d\n", length);
    
    // 复制字符串
    strcpy(result, str1);
    printf("Copied string: %s\n", result);
    
    // 连接字符串
    strcat(result, " ");
    strcat(result, str2);
    printf("Concatenated string: %s\n", result);
    
    // 比较字符串
    compare = strcmp(str1, str2);
    if (compare < 0) {
        printf("%s comes before %s\n", str1, str2);
    } else if (compare > 0) {
        printf("%s comes after %s\n", str1, str2);
    } else {
        printf("%s is equal to %s\n", str1, str2);
    }
    
    // 格式化输出到字符串
    sprintf(result, "%s %s - Length: %d", str1, str2, length);
    printf("Formatted string: %s\n", result);
    
    // 查找子字符串
    char *pos = strstr(result, "World");
    if (pos) {
        printf("Found 'World' at position: %d\n", pos - result);
    }
    
    return 0;
}

输出结果

Length of str1: 5
Copied string: Hello
Concatenated string: Hello World
Hello comes before World
Formatted string: Hello World - Length: 5
Found 'World' at position: 6