Question

EDIT:为了回答某些问题,这是订正的、仍然不可行的法典(其中多数是先开始的,但我本应明确表明,我已初步提出档案点等)。再说一遍,如果我要么在(a)项之前加上一封信,要么完全删除(a)项,那就行了。

FILE *outfile;
char *outfilename;
outfilename = (char *)malloc(FILENAME_MAX*sizeof(char));
strcpy(outfilename, "outfile.txt");
outfile = fopen(realoutfilename, "w");

/* If this is uncommented, there isn t a segfault
if(realoutfile!=NULL && imoutfile!=NULL){
    fprintf(outfile, "
");
    fseek(outfile,0,SEEK_SET);
}
*/

gauss = (double*) calloc(points, sizeof(double));

/* Maths and stuff */

if(outfile!=NULL){
    for(i=0;i<points;i++){
        /* this prints fine */
        printf(outfile, "%g,
", gauss[i]);
        /* Seg fault is here */
        fprintf(outfile, "%g,
", gauss[i]);

    }
}
fclose(outfile);
free(outfile);

• 编辑:

gcc main.c -lm - Wall - Wextra - Werror - Wshadow -g -o main

为了澄清,它没有达到功能的结束,因此它没有放弃它坠毁。坠毁时正试图在案卷中写上 lo。

我检查一下,正如我所说的那样,支出是拖长或流入不足的,我可以打印产出,但书面文件是没有的。如果我试图用简单的话说话,就失败了。

背书是(不熟悉 g,认为它可能有助于):

#0  0xff15665c in _malloc_unlocked () from /lib/libc.so.1
#1  0xff15641c in malloc () from /lib/libc.so.1
#2  0xff1a8c80 in _findbuf () from /lib/libc.so.1
#3  0xff1a8f0c in _wrtchk () from /lib/libc.so.1
#4  0xff1ad834 in _fwrite_unlocked () from /lib/libc.so.1
#5  0xff1ad798 in fwrite () from /lib/libc.so.1
#6  0x000128ac in gaussian ()
#7  0x00010f78 in main ()

任何帮助都将受到高度赞赏。

Answer 1

The problem, is here:

outfilename = (char *)malloc(FILENAME_MAX*sizeof(char));
outfilename = "file.txt";

You can t assign a string like that, you have to use strcpy:

strcpy(outfilename, "file.txt");

发生的情况是,你重写了<编码>>outfilename号指示,该指示号指代号。之后,您尝试免费发放<代码>;。由于你释放了直截了当的字面,行为没有定义,因此你正在坠毁。

为什么它坠毁于一起而不是另一起案件。行为不明确,因此任何事情都允许发生。您的成指数功能代码有可能对可能造成坠毁/失事的 st/飞跃有所作为。

http://www.un.org。我希望这只是一个打字或错误的复印件,但我也看不到在什么地方启用了<代码>outfile。如果它实际上从未开始,那就会产生另一个错误。 (很可能是造成你特别陷阱)

So it should look like this:

FILE *outfile;
outfilename = (char *)malloc(FILENAME_MAX*sizeof(char));
strcpy(outfilename, "file.txt");

outfile = fopen(outfilename, "w");
if (outfile == NULL){
    //  Error, file cannot be openned.
}

Answer 2

首先,您应实际编辑的所有警报和生成的信息;gcc。这意味着<代码>-Wall -g。

FILE *outfile;
outfilename = (char *)malloc(FILENAME_MAX*sizeof(char));
outfilename = "file.txt";

页: 1 页: 1

 outfile = fopen(outfilename, "r");

And you should learn to use the debugger gdb (or perhaps its ddd graphical front-end).

Answer 3

outfilename = "file.txt";
/* snip */
free(outfilename);

You can only free something you got back from malloc. You can t pass free a pointer to a constant!

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