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下面是我的程序。我正在创建一个结构，使用 malloc 分配内存，因为我想要一个非常大的结构数组，然后将该结构数组传递给函数。功能并不重要，因为我无法离开主程序。我的困惑是我的编译器（gcc）说当我尝试释放每个事件时未声明它，但没有其他地方。当我注释掉它编译的自由语句时，但是 valgrind 说当我执行 each_event[i].timestamp = tim[i] 行时，我有一个大小为 4 的无效写入。上面的行被注释掉了，因为 valgrind 告诉我错误在那里（我用 gcc -g -O0 编译），即使我知道它必须表示下面的行。

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

#define event_length 512
#define bits_n_byte 8
#define timestamp_bytes 8

typedef enum type {
    DATA, CLOCK, EXPECTED, SPILL, ALL
} type;

typedef struct event {
char clocbuffer[event_length*bits_n_byte];
char datbuffer[event_length*bits_n_byte];
char expect[event_length];
char spil[event_length];
char clocerror[event_length*bits_n_byte];
char daterror[event_length*bits_n_byte];
long unsigned int timestamp;
} event;

int i, j, k, l, length, nevents;
char **spil, **expect, **dat, **cloc, **clocerror, **daterror;
long unsigned int *tim;
char library[256];
char *runnum, *clocmode, *datmode;

void GetPiece(char*, type, struct event*);
void FindMode(type);
void ErrorPiece(type);

int main(int argc,char **argv) {
if (argc != 2) {fprintf(stderr, "Format: ./program #_patterns\nTry again.\n");}

for (i=0;i<256;i++) library[i]=i;

FILE *IN = NULL;
char *buffer = NULL;

runnum = (char *) malloc(2);
runnum = strncpy(runnum,argv[1],1);
runnum[1] = '\0';
IN=fopen(argv[1], "r");                 /*Open input file.*/

if (IN)
{
    fseek(IN, 0, SEEK_END);                 /*This finds  */
    length  = ftell(IN);                    /*the length  */
    fseek(IN, 0, SEEK_SET);                 /*of the file.*/
    buffer = malloc(length + 2);            /*for buffer.     */
    fread(buffer, 1, length, IN);
    tim = (long unsigned int *) malloc(length + 2*sizeof(long unsigned int));
    fread(tim, sizeof(long unsigned int), length/sizeof(long unsigned int), IN);
    fclose(IN);

    nevents = length/2056;
    struct event* each_event = (struct event *) malloc(nevents*sizeof(struct event));

    for (i=0; i<length/sizeof(unsigned long int); i+=2056/sizeof(unsigned long int))
    {
    tim[i] = __builtin_bswap32 (tim[i]);
    tim[i]-=0x80000000;
    //if (tim[i]<1200000000 || tim[i]>1300000000) fprintf(stderr, "Check timestamp. Either endianness, size of bytes, or size of long ints are different.");
    each_event[i].timestamp = tim[i];
    }

    clocmode = malloc(nevents);
    datmode = malloc(nevents);

    GetPiece(buffer, DATA, each_event);
    GetPiece(buffer, CLOCK, each_event);
    GetPiece(buffer, EXPECTED, each_event);
    GetPiece(buffer, SPILL, each_event);
    GetPiece(buffer, ALL, each_event);
    FindMode(DATA);
    FindMode(CLOCK);
    ErrorPiece(DATA);
    ErrorPiece(CLOCK);
}
else fprintf(stderr,"Error in file naming/opening.\n");   /*error*/
free (buffer);
free (tim);
free (runnum);
free (clocmode);
free (datmode);
free (each_event);
return 0;}
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1 回答 1

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因为each_event是在if { ... }块内声明的，所以当你尝试free()它时它已经超出了范围。要么在 的末尾释放它，要么在 .if { ... }的开头将声明与其他声明一起放入main()。但是，如果您执行后者，您可能会收到有关它可能在未初始化的情况下被使用的警告，因此第一个选项可能是最好的。

于 2012-06-20T15:13:29.467 回答