urlencode编码与解码 C++

在 C 语言中，可以使用以下库函数来进行 urlencode 编码和解码：

1. urlencode 编码：

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

char* urlencode(char* str) {
    int len = strlen(str);
    char* encoded = (char*)malloc(len * 3 + 1);
    int j = 0;
    for (int i = 0; i < len; i++) {
        if (isalnum(str[i]) || str[i] == '-' || str[i] == '_' || str[i] == '.' || str[i] == '~') {
            encoded[j++] = str[i];
        } else if (str[i] == ' ') {
            encoded[j++] = '+';
        } else {
            sprintf(encoded + j, "%%%02X", str[i]);
            j += 3;
        }
    }
    encoded[j] = '\0';
    return encoded;
}

2. urlencode 解码：

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

char* urldecode(char* str) {
    int len = strlen(str);
    char* decoded = (char*)malloc(len + 1);
    int j = 0;
    for (int i = 0; i < len; i++) {
        if (str[i] == '+') {
            decoded[j++] = ' ';
        } else if (str[i] == '%') {
            char hex[3] = { str[i + 1], str[i + 2], '\0' };
            decoded[j++] = strtol(hex, NULL, 16);
            i += 2;
        } else {
            decoded[j++] = str[i];
        }
    }
    decoded[j] = '\0';
    return decoded;
}

使用示例：

#include <stdio.h>
#include <stdlib.h>

int main() {
    char* str = "hello world!";
    char* encoded = urlencode(str);
    printf("Encoded: %s\n", encoded);
    char* decoded = urldecode(encoded);
    printf("Decoded: %s\n", decoded);
    free(encoded);
    free(decoded);
    return 0;
}

输出结果：

Encoded: hello+world%21
Decoded: hello world!