从 C 中的函数返回数组到 main

Question

所以基本上我的问题是我想要解压缩函数对“printf("%.*s", repeat, memset(set, c, repeat));”的输出进行签名到数组 dest 和 return 这个 dest 到 main 并将其签名到 Decompressed_Message

这是我的问题的图片

我想要第一个解压版本：和第二个完全一样。但是，即使我尝试了sprintf()，我还是无法如愿

这是我的代码

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <ncurses.h>
    
char* Compression(char* Message, int given_count)
{
    int Len;
    char count[given_count];
    int length = strlen(Message);
     
    char* destination = (char*)malloc(sizeof(char) * (length * 2 + 1));
        
    int i;
    int j=0;
    int k;
     
    for (i = 0; i < length; i++) {
        destination[j++] = Message[i];
        Len = 1;
        while (i + 1 < length && Message[i] == Message[i + 1]) {
            Len++;
            i++;
        }
     
        sprintf(count, "%d", Len);
     
        for (k = 0; *(count + k); k++, j++) {
            destination[j] = count[k];
        }
    }
    destination[j] = '[=10=]';
    return destination;
    free(destination);
}
    
char* Decompression(char *Compressed_Message, char* Message){
        
    int length = strlen(Message);
    char* dest = (char*)malloc(sizeof(char) * (length * 2 + 1));
        
    while(*Compressed_Message){
        int repeat = 0;
        char c = *Compressed_Message++;   
        while(isdigit(*Compressed_Message))
        {
            repeat = repeat*10 + *Compressed_Message++ - '0'; 
        }
        char set[repeat];
        printf("%.*s", repeat, memset(set, c, repeat)); 
        memset(dest, c, repeat);
    }
        
    dest[length] = '[=10=]';
    return dest;
    free(dest);
}
        
int main(void) {
    
    int letters;
    float compression_odd;
    
    printf("Data compressor and decompressor\n\n");
        
    FILE *file;
    char filename[100]="";  
    printf("\n\nPlease Enter the name of file: ");
    scanf("%99s",filename);
    file=fopen(filename,"r");
    if(file==NULL){
        printf("\n%s File not found.\n\n",filename);
        exit(1);
    }
        
    fseek(file, 0, SEEK_END);
    long count = ftell(file);
    fseek(file, 0, SEEK_SET);
        
    char Message[count];
        
    fread(Message, strlen(Message)+1, count, file);  
    Message[count]='[=10=]';
        
    printf("\nMessage: %s\n", Message);
        
    printf("char number of message: %d\n", strlen(Message));
    printf("\nCompressed version: ");
    char* Compressed_Message = Compression(Message, count);
    printf("\n");
    printf("%s", Compressed_Message);
    printf("\nchar number of compressed message: %d\n", strlen(Compressed_Message));
    compression_odd = ((strlen(Message) - strlen(Compressed_Message)) * 100) / strlen(Message);
        
    if (compression_odd > 100 || compression_odd < 0){
        printf("\nCompression ratio is negative Message got longer !\n");
    }
    else{
        printf("\nCompression Ratio is approximately: %.2f", compression_odd);
    }
    
    printf("\nDecompressed version: ");
    char* Decompressed_Message = Decompression(Compressed_Message, Message);
        
    printf("\nDecompressed version: %s", Decompressed_Message);
        
    /*if (strcmp(Message, DecompressedSize) == 0) {
      printf("\nCompression done.\n");
      } else {
      printf("\nCompression crushed!\n");
      }*/
    fclose(file);
    return 0;
}

Answer 1

你的 Decompression() 功能有几个问题。

char* dest = (char*)malloc(sizeof(char) * (length * 2 + 1));

这没有分配足够大的目的地。例如，如果压缩字符串是 a100，目标至少需要 101 个字符，但您只会分配 9 个字符。如果不读取所有重复计数，就无法知道目的地需要多大；您应该使用 realloc().

逐步增加目的地

在 while 循环中，您不断将每个重复的字符复制到 dest，而不是在前一个块之后复制它。所以最后，它只包含最后一个重复的字符，而不是全部。

您不需要 set 数组。您可以将 memset() 直接用于 dest（在添加调整以附加到前一个块之后）并按照您打印的方式打印 set.

char* Decompression(char *Compressed_Message, char* Message){
        
    int length = 0;
    char* dest = NULL;
        
    while(*Compressed_Message){
        int repeat = 0;
        char c = *Compressed_Message++;   
        while(isdigit(*Compressed_Message))
        {
            repeat = repeat*10 + *Compressed_Message++ - '0'; 
        }
        dest = realloc(dest, length + repeat + 1);
        printf("%.*s", repeat, memset(dest + length, c, repeat)); 
        length += repeat;
    }
        
    dest[length] = '[=11=]';
    return dest;
}

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