Question

我目前正在开发一个项目，其中一个给定的函数似乎编译得很好，但是没有正常工作。

    void tsunamiWriteFile(const char *baseResultName, int iter, double *U, double *V, double *E, int nelem, int nsub){
    int i,j;
    const char *basename = "%s-%08d.txt";
    char filename[256];
    sprintf(filename,basename,baseResultName,iter);
    FILE* file = fopen(filename,"w");
    fprintf(file, "Number of elem %d \n", nelem);
    ...
    ... }

当我用valgrind运行程序时，我得到了这个：

    ==4993== Invalid read of size 4
    ==4993==    at 0x59D3778: __fprintf_chk (fprintf_chk.c:32)
    ==4993==    by 0x4081B4: tsunamiWriteFile (stdio2.h:98)
    ==4993==    by 0x408363: tsunamiCompute (tsunami.c:228)
    ==4993==    by 0x401714: main (mainCompute.c:10)
    ==4993==  Address 0x0 is not stack'd, malloc'd or (recently) free'd

任何想法为什么fprintf不起作用？

Answer 1

错误：

Address 0x0 is not stack'd, malloc'd or (recently) free'd.

表示已收到NULL指针且该函数尝试取消引用它。

您需要检查fopen返回的指针：

if ((file = fopen(filename, "w")) != NULL)
    fprintf(file, ...);
else
    perror("fopen");

使用fprintf读取无效

1 个答案: