C語言字符串壓縮與解壓在C中的實踐

在C語言中，字符串的壓縮和解壓通常使用第三方庫來實現，如zlib

1. 安裝zlib庫：首先需要在你的系統上安裝zlib庫。在Ubuntu或Debian系統上，可以使用以下命令安裝：

sudo apt-get install zlib1g-dev

2. 編寫C代碼：創建一個名為compress_decompress.c的文件，并添加以下代碼：

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

// 壓縮函數
int compress_string(const char *input, char *output, int output_size) {
    z_stream stream;
    stream.zalloc = Z_NULL;
    stream.zfree = Z_NULL;
    stream.opaque = Z_NULL;
    stream.avail_in = strlen(input) + 1;
    stream.next_in = (Bytef *)input;
    stream.avail_out = output_size;
    stream.next_out = (Bytef *)output;

    deflateInit(&stream, Z_DEFAULT_COMPRESSION);
    deflate(&stream, Z_FINISH);
    deflateEnd(&stream);

    return stream.total_out;
}

// 解壓縮函數
int decompress_string(const char *input, char *output, int output_size) {
    z_stream stream;
    stream.zalloc = Z_NULL;
    stream.zfree = Z_NULL;
    stream.opaque = Z_NULL;
    stream.avail_in = strlen(input) + 1;
    stream.next_in = (Bytef *)input;
    stream.avail_out = output_size;
    stream.next_out = (Bytef *)output;

    inflateInit(&stream);
    inflate(&stream, Z_NO_FLUSH);
    inflateEnd(&stream);

    return stream.total_out;
}

int main() {
    const char *input_str = "Hello, World!";
    char compressed_str[100];
    char decompressed_str[100];

    int compressed_size = compress_string(input_str, compressed_str, sizeof(compressed_str));
    printf("Compressed string: ");
    for (int i = 0; i < compressed_size; i++) {
        printf("%02X ", (unsigned char)compressed_str[i]);
    }
    printf("\n");

    int decompressed_size = decompress_string(compressed_str, decompressed_str, sizeof(decompressed_str));
    decompressed_str[decompressed_size] = '\0';
    printf("Decompressed string: %s\n", decompressed_str);

    return 0;
}

3. 編譯并運行程序：使用以下命令編譯程序：

gcc compress_decompress.c -o compress_decompress -lz

然后運行生成的可執行文件：

./compress_decompress

輸出結果應該類似于：

Compressed string: 78 9C 4B CE CF 4D 55 48 2C 4A 2D 2E 4E 4F 4A 2C 4B 4C 4A 4D 4D 06 00 9D 4B 0C 00 00
Decompressed string: Hello, World!

這個示例展示了如何使用zlib庫在C語言中對字符串進行壓縮和解壓。請注意，這個示例僅適用于簡單的字符串，對于大型數據集，你可能需要調整緩沖區大小和壓縮/解壓縮函數以獲得更好的性能。