帮我用c语言写一个利用Huffan编码实现文件压缩

好的，我可以为您提供一个简单的C语言实现。以下代码实现了文件的压缩和解压功能：

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

#define MAX_TREE_HT 256
#define MAX_FILENAME 100

// 定义哈夫曼树节点
struct HuffmanNode {
    char data;
    int freq;
    struct HuffmanNode *left;
    struct HuffmanNode *right;
};

// 定义哈夫曼编码
struct HuffmanCode {
    char data;
    char code[MAX_TREE_HT];
};

// 统计字符出现频率
void countFrequency(FILE *fp, int *freq) {
    char ch;
    while ((ch = fgetc(fp)) != EOF) {
        freq[ch]++;
    }
}

// 创建哈夫曼树节点
struct HuffmanNode *createNode(char data, int freq) {
    struct HuffmanNode *node = (struct HuffmanNode *) malloc(sizeof(struct HuffmanNode));
    node->data = data;
    node->freq = freq;
    node->left = node->right = NULL;
    return node;
}

// 创建哈夫曼树
struct HuffmanNode *buildHuffmanTree(int *freq) {
    int i;
    struct HuffmanNode *node, *left, *right;
    struct MinHeap *heap = createMinHeap(MAX_TREE_HT);

    for (i = 0; i < MAX_TREE_HT; i++) {
        if (freq[i] > 0) {
            node = createNode((char) i, freq[i]);
            insertMinHeap(heap, node);
        }
    }

    while (heap->size > 1) {
        left = deleteMinHeap(heap);
        right = deleteMinHeap(heap);
        node = createNode('\0', left->freq + right->freq);
        node->left = left;
        node->right = right;
        insertMinHeap(heap, node);
    }

    node = deleteMinHeap(heap);
    destroyMinHeap(heap);

    return node;
}

// 生成哈夫曼编码
void generateHuffmanCode(struct HuffmanNode *node, char *code, int len, struct HuffmanCode *hCodes) {
    if (node == NULL) {
        return;
    }

    if (node->left == NULL && node->right == NULL) {
        hCodes[node->data].data = node->data;
        hCodes[node->data].code[len] = '\0';
        strcpy(hCodes[node->data].code, code);
        return;
    }

    code[len] = '0';
    generateHuffmanCode(node->left, code, len + 1, hCodes);

    code[len] = '1';
    generateHuffmanCode(node->right, code, len + 1, hCodes);
}

// 将哈夫曼编码写入文件
void writeHuffmanCode(FILE *fp, struct HuffmanCode *hCodes, int *freq) {
    int i, j;
    char ch;

    fwrite(freq, sizeof(int), MAX_TREE_HT, fp);

    for (i = 0; i < MAX_TREE_HT; i++) {
        if (freq[i] > 0) {
            ch = (char) i;
            fwrite(&ch, sizeof(char), 1, fp);
            fwrite(hCodes[i].code, sizeof(char), strlen(hCodes[i].code), fp);
        }
    }
}

// 从文件中读取哈夫曼编码
struct HuffmanNode *readHuffmanCode(FILE *fp, int *freq) {
    int i, j, len;
    char ch, *code;
    struct HuffmanNode *root = NULL;
    struct HuffmanNode *node = NULL;

    fread(freq, sizeof(int), MAX_TREE_HT, fp);

    for (i = 0; i < MAX_TREE_HT; i++) {
        if (freq[i] > 0) {
            ch = (char) i;
            code = (char *) malloc(sizeof(char) * (MAX_TREE_HT + 1));
            fread(code, sizeof(char), MAX_TREE_HT, fp);
            node = createNode(ch, freq[i]);
            if (root == NULL) {
                root = node;
            }
            for (j = 0, len = strlen(code); j < len; j++) {
                if (code[j] == '0') {
                    if (node->left == NULL) {
                        node->left = createNode('\0', 0);
                    }
                    node = node->left;
                } else if (code[j] == '1') {
                    if (node->right == NULL) {
                        node->right = createNode('\0', 0);
                    }
                    node = node->right;
                }
            }
            free(code);
        }
    }

    return root;
}

// 压缩文件
void compressFile(char *filename, struct HuffmanCode *hCodes) {
    int i, len;
    char ch, *code;
    FILE *fpin, *fpout;

    fpin = fopen(filename, "rb");
    if (fpin == NULL) {
        printf("Error: cannot open file %s\n", filename);
        return;
    }

    len = strlen(filename);
    filename[len - 3] = 'h';
    filename[len - 2] = 'f';
    filename[len - 1] = 'c';
    fpout = fopen(filename, "wb");
    if (fpout == NULL) {
        printf("Error: cannot create file %s\n", filename);
        return;
    }

    int freq[MAX_TREE_HT] = {0};
    countFrequency(fpin, freq);
    struct HuffmanNode *root = buildHuffmanTree(freq);
    generateHuffmanCode(root, code, 0, hCodes);
    writeHuffmanCode(fpout, hCodes, freq);

    rewind(fpin);
    code = (char *) malloc(sizeof(char) * (MAX_TREE_HT + 1));
    while ((ch = fgetc(fpin)) != EOF) {
        strcpy(code, hCodes[ch].code);
        for (i = 0, len = strlen(code); i < len; i++) {
            if (code[i] == '0') {
                fwrite("0", sizeof(char), 1, fpout);
            } else if (code[i] == '1') {
                fwrite("1", sizeof(char), 1, fpout);
            }
        }
    }
    free(code);

    fclose(fpin);
    fclose(fpout);

    printf("File %s is compressed successfully!\n", filename);
}

// 解压文件
void decompressFile(char *filename, struct HuffmanNode *root) {
    int i;
    char ch, bit;
    FILE *fpin, *fpout;

    fpin = fopen(filename, "rb");
    if (fpin == NULL) {
        printf("Error: cannot open file %s\n", filename);
        return;
    }

    int freq[MAX_TREE_HT] = {0};
    readHuffmanCode(fpin, freq);
    root = readHuffmanCode(fpin, freq);

    char newfilename[MAX_FILENAME];
    int len = strlen(filename);
    strncpy(newfilename, filename, len - 3);
    newfilename[len - 3] = 'u';
    newfilename[len - 2] = 'n';
    newfilename[len - 1] = 'c';
    fpout = fopen(newfilename, "wb");
    if (fpout == NULL) {
        printf("Error: cannot create file %s\n", newfilename);
        return;
    }

    struct HuffmanNode *node = root;
    while ((ch = fgetc(fpin)) != EOF) {
        for (i = 7; i >= 0; i--) {
            bit = (ch & (1 << i)) ? '1' : '0';
            if (bit == '0') {
                node = node->left;
            } else if (bit == '1') {
                node = node->right;
            }
            if (node->left == NULL && node->right == NULL) {
                fwrite(&node->data, sizeof(char), 1, fpout);
                node = root;
            }
        }
    }

    fclose(fpin);
    fclose(fpout);

    printf("File %s is decompressed successfully!\n", filename);
}

int main() {
    int op;
    char filename[MAX_FILENAME];
    struct HuffmanCode hCodes[MAX_TREE_HT] = {{0}};
    struct HuffmanNode *root = NULL;

    while (1) {
        printf("1. Compress file\n");
        printf("2. Decompress file\n");
        printf("3. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &op);

        switch (op) {
            case 1:
                printf("Enter filename to compress: ");
                scanf("%s", filename);
                compressFile(filename, hCodes);
                break;
            case 2:
                printf("Enter filename to decompress: ");
                scanf("%s", filename);
                decompressFile(filename, root);
                break;
            case 3:
                exit(0);
        }
    }

    return 0;
}

希望这个代码对您有帮助！