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realloc:返回损坏的数据

corrupt-data realloc c

1

Nabila K · 技术社区 · 7 年前

realloc 我收到损坏的数据。我真的不知道问题出在哪里。

char *read_string(FILE *fichier) {
    char car = 0;
    size_t size = 1;
    char *symbole = realloc(NULL, sizeof(char) * size);
    char *s; 
    size_t len = 0;
    if (!symbole)
        return symbole;
    else
        s = symbole; 
    do {
        car = getc(fichier);
    } while (car != '"' && car != EOF);
    if (car == EOF)
        return EOFP; 
    else {
        car = getc(fichier);
        while (car != '"' ) {
            s[len] = car;
            car = getc(fichier);
            len++;
            if (len == size) {
                symbole = realloc(s, sizeof(char) * (size += 1));
                if (!symbole)
                    return symbole;
                else
                    s = symbole; 
            }
        }
        s[len] = '\0' ;
        symbole = realloc(s, sizeof(char) * len);
        if (!symbole) {
            printf("WTF");
            return symbole;
        } else
            s = symbole;  
        return s;
    }
}

main

int main(int argc, char *argv[]) {

    FILE *fichier = NULL;
    fichier = fopen("C:/Users/Nabila K/Documents/test.json", "r");

    if ((fichier != NULL)) {
        while (feof(fichier) == 0) {
            char *test = read_string(fichier);
            if (test == NULL) {
                printf("test == NULL\n");
                exit(1);
            } else
            if (test == EOFP) {
            } else {
                printf("%s\n", test);
                free(test);
            } 
        } 
        fclose(fichier);   
    } else {
        exit(EXIT_FAILURE);
    }
    return 0;
}

我的json文件如下所示:

{
    "KARIM BENNI" : {
       "2017-08-07 09:50:50" : {
          "Anomalie" : {
            "description" : "Test",
            "theme" : "Engins mobiles"
          },
          "date" : "2017-08-07",
          "date_now" : "2017-08-07 09:50:50",
          "entite" : "USINE LAMINAGE A FROID",
          "etat" : "Cree",
          "nb_personne" : 2,
          "temps" : 5,
          "visiteur" : "KARIM BENNI",
          "visite" : "AHMED RABII",
          "zone" : "COUPE"
       }
    }
    }

1 回复 | 直到 7 年前

1

3

chqrlie 4 年前

您的代码中存在多个问题:

char car = 0; 不正确:必须定义 car int 要正确区分返回的所有值 getc() EOF .
while (feof(fichier) == 0) Why is âwhile ( !feof (file) )â always wrong?
EOFP NULL 相反,为了更清晰。
决赛 realloc() 到分配的块太短一个字节。你必须保持 len+1 字节 len 角色空终止符。

以下是一个简化和更正的版本:

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

char EOFP[1];   /* special value used to signal end of file */

char *read_string(FILE *file) {
    int c;
    size_t size, len;
    char *symbol;
    char *s;

    while ((c = getc(file)) != '"') {
        if (c == EOF)
            return EOFP;
    }
    size = 16;
    len = 0;
    symbol = malloc(size);
    if (symbol == NULL) {
        /* allocation failure */
        return NULL;
    }
    while ((c = getc(file)) != '"') {
        if (c == EOF) {
            /* premature end of file in the middle of a string */
            free(symbol);
            return EOFP;
        }
        if (len + 2 < size) {
            size += size;
            s = realloc(symbol, size);
            if (s == NULL) {
                /* allocation failure */
                free(symbol);
                return NULL;
            }
            symbol = s;
        }
        symbol[len++] = c;
    }
    symbol[len] = '\0';
    s = realloc(symbol, len + 1);
    return s ? s : symbol;
}

int main(int argc, char *argv[]) {

    FILE *file = fopen("C:/Users/Nabila K/Documents/test.json", "r");
    if (file != NULL)) {
        char *test;
        while ((test = read_string(file)) != EOFP) {
            if (test == NULL) {
                printf("test == NULL\n");
                exit(1);
            } else {
                printf("%s\n", test);
                free(test);
            }
        } 
        fclose(file);   
    } else {
        exit(EXIT_FAILURE);
    }
    return 0;
}

如果字符串可以包含转义字符,例如 \" 或 \n , \\