Question

我想要做的就是读取文件内容并将它们放到字符串中从文件中读取时出现问题。我开始用fgets阅读，如果我的空间不够，我会重新分配内存。但是，当我尝试再次重新分配以缩小时，它会崩溃。我读到它可能与malloc的元数据有关，但我看不出我是如何影响它们的。提前致谢

 int readStringFromALE(int height,int width,char **stringImage,FILE *fout){
    char buffer[BUFFER_SIZE] = {'\0'};
    *stringImage=(char *)malloc(sizeof(char)*BUFFER_SIZE+1);
    *stringImage[0]='\0';
    int i=1;
    int size=sizeof(char)*BUFFER_SIZE,readSize=0;
    while(fgets(buffer, sizeof(buffer), fout) != NULL){
        strncat(*stringImage,buffer,strlen(buffer)+1);
        readSize+=strlen(buffer)+1;
        printf("%s",buffer);
        if(size<=readSize){
            char *temp;
            temp=(char *)realloc(*stringImage,i*BUFFER_SIZE*sizeof(char)+1);
            if(temp==NULL){
                printf("Unable to allocate memory\n");
                return EXIT_FAILURE;
            }
            i++;
            *stringImage=temp;
            size=i*BUFFER_SIZE*sizeof(char);
        }
        if (buffer[strlen(buffer) - 2] == ':')
            break;
    }
    char *temp=(char *)realloc(*stringImage,strlen(*stringImage)+10);
    if(temp==NULL){
        printf("Unable to allocate memory\n");
        return EXIT_FAILURE;
    }
    *stringImage=temp;
    return EXIT_SUCCESS;
}

Answer 1

尝试在每次调用时使用fgets读取字符串末尾（* stringImage + len）。

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

#define BUFFER_SIZE 10

int readStringFromALE(int height,int width,char **stringImage,FILE *fout){
    char *temp = NULL;
    size_t size = 0;
    size_t dif = 0;
    size_t len = 0;

    while ( 1) {
        if ( NULL == ( temp = realloc ( *stringImage, size + BUFFER_SIZE))) {
            fprintf ( stderr, "problem realloc\n");
            free ( *stringImage);
            return 0;
        }
        *stringImage = temp;
        //len = strlen ( *stringImage);
        dif = BUFFER_SIZE + ( size - len);
        if ( fgets ( *stringImage + len, dif, fout)) {
            len += strlen ( *stringImage + len);
            if ((*stringImage)[strlen(*stringImage) - 2] == ':')
                break;
        }
        else {
            printf("\n\n---end of file---\n");
            break;
        }
        size += BUFFER_SIZE;
    }
    temp=(char *)realloc(*stringImage,strlen(*stringImage)+10);
    if(temp==NULL){
        printf("Unable to allocate memory\n");
        return EXIT_FAILURE;
    }
    *stringImage=temp;
    return EXIT_SUCCESS;
}

int main(int argc,char** argv){
    char *stringImage = NULL;//so realloc will act like malloc on first call
    int height = 0;
    int width = 0;
    FILE *fout = NULL;

    if ( NULL == ( fout = fopen ( "somefile.txt", "r"))) {
        perror ( "problem");
        return 0;
    }

    readStringFromALE( height, width, &stringImage, fout);
    fclose ( fout);
    printf("%s\n\n",stringImage);

    free ( stringImage);

    return 0;
}

使用文件

1 个答案: