有哈夫曼码表，如何对本地文本进行压缩C语言编程的代码

首先，需要将文本文件读入到程序中。然后，统计文本中各个字符的频率，并按照频率建立哈夫曼树。接下来，根据哈夫曼树生成哈夫曼编码表。最后，将文本内容进行哈夫曼编码，将编码后的二进制数据保存到文件中。

下面是一个简单的实现例子：

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

// 定义哈夫曼编码结构体
typedef struct HuffmanCode {
    int freq;               // 字符出现频率
    char code[256];         // 哈夫曼编码
} HuffmanCode;

// 定义哈夫曼树节点结构体
typedef struct TreeNode {
    int freq;               // 字符出现频率
    int symbol;             // 字符
    struct TreeNode *left;  // 左子树
    struct TreeNode *right; // 右子树
} TreeNode;

// 统计文本中各个字符的频率
int *calcFreq(FILE *fp, int *size) {
    int *freq = (int *)calloc(256, sizeof(int));
    if (freq == NULL) {
        printf("error: memory allocation failed\n");
        exit(EXIT_FAILURE);
    }

    int ch;
    while ((ch = fgetc(fp)) != EOF) {
        freq[ch]++;
    }

    *size = ftell(fp);
    fseek(fp, 0, SEEK_SET);

    return freq;
}

// 创建哈夫曼树
TreeNode *createHuffmanTree(int *freq) {
    TreeNode **nodes = (TreeNode **)calloc(256, sizeof(TreeNode *));
    if (nodes == NULL) {
        printf("error: memory allocation failed\n");
        exit(EXIT_FAILURE);
    }

    // 初始化节点
    for (int i = 0; i < 256; i++) {
        if (freq[i] > 0) {
            nodes[i] = (TreeNode *)calloc(1, sizeof(TreeNode));
            if (nodes[i] == NULL) {
                printf("error: memory allocation failed\n");
                exit(EXIT_FAILURE);
            }

            nodes[i]->freq = freq[i];
            nodes[i]->symbol = i;
        }
    }

    // 构建哈夫曼树
    while (1) {
        TreeNode *node1 = NULL;
        TreeNode *node2 = NULL;

        // 找到频率最小的两个节点
        for (int i = 0; i < 256; i++) {
            if (nodes[i] != NULL) {
                if (node1 == NULL || nodes[i]->freq < node1->freq) {
                    node2 = node1;
                    node1 = nodes[i];
                } else if (node2 == NULL || nodes[i]->freq < node2->freq) {
                    node2 = nodes[i];
                }
            }
        }

        if (node2 == NULL) {
            break;
        }

        // 创建新节点
        TreeNode *node = (TreeNode *)calloc(1, sizeof(TreeNode));
        if (node == NULL) {
            printf("error: memory allocation failed\n");
            exit(EXIT_FAILURE);
        }

        node->freq = node1->freq + node2->freq;
        node->left = node1;
        node->right = node2;

        nodes[node1->symbol] = node;
        nodes[node2->symbol] = NULL;
    }

    // 返回根节点
    return nodes[node1->symbol];
}

// 生成哈夫曼编码表
void createHuffmanCode(TreeNode *node, HuffmanCode *codes, char *code, int size) {
    if (node->left == NULL && node->right == NULL) {
        // 叶子节点，将哈夫曼编码赋值到编码表中
        codes[node->symbol].freq = node->freq;
        strcpy(codes[node->symbol].code, code);
    } else {
        // 非叶子节点，向左子树添加编码位 '0'
        code[size] = '0';
        createHuffmanCode(node->left, codes, code, size + 1);

        // 向右子树添加编码位 '1'
        code[size] = '1';
        createHuffmanCode(node->right, codes, code, size + 1);
    }
}

// 哈夫曼编码
void huffmanEncode(FILE *fp, FILE *outfp, HuffmanCode *codes) {
    char *code = (char *)calloc(256, sizeof(char));
    if (code == NULL) {
        printf("error: memory allocation failed\n");
        exit(EXIT_FAILURE);
    }

    int ch;
    int pos = 0;
    char buf = 0;

    while ((ch = fgetc(fp)) != EOF) {
        // 将哈夫曼编码拼接到缓冲区中
        for (int i = 0; codes[ch].code[i] != '\0'; i++) {
            if (codes[ch].code[i] == '0') {
                buf = buf << 1;
            } else {
                buf = (buf << 1) | 1;
            }

            pos++;

            if (pos == 8) {
                // 缓冲区已满，写入文件中
                fwrite(&buf, sizeof(char), 1, outfp);
                pos = 0;
                buf = 0;
            }
        }
    }

    // 写入剩余数据
    if (pos > 0) {
        buf = buf << (8 - pos);
        fwrite(&buf, sizeof(char), 1, outfp);
    }
}

int main(void) {
    FILE *fp = fopen("test.txt", "rb");
    if (fp == NULL) {
        printf("error: file not found\n");
        return EXIT_FAILURE;
    }

    int size;
    int *freq = calcFreq(fp, &size);
    TreeNode *root = createHuffmanTree(freq);
    HuffmanCode *codes = (HuffmanCode *)calloc(256, sizeof(HuffmanCode));
    if (codes == NULL) {
        printf("error: memory allocation failed\n");
        return EXIT_FAILURE;
    }

    char *code = (char *)calloc(256, sizeof(char));
    if (code == NULL) {
        printf("error: memory allocation failed\n");
        return EXIT_FAILURE;
    }

    createHuffmanCode(root, codes, code, 0);

    FILE *outfp = fopen("test.bin", "wb");
    if (outfp == NULL) {
        printf("error: file create failed\n");
        return EXIT_FAILURE;
    }

    huffmanEncode(fp, outfp, codes);

    fclose(outfp);
    fclose(fp);

    free(freq);
    free(codes);
    free(code);

    return 0;
}

这个程序能够读取名为 `test.txt` 的文本文件，使用哈夫曼编码进行压缩，并将压缩后的二进制数据保存为名为 `test.bin` 的文件。