使用 fopen 时出现段错误 [英] Segfault while using fopen

问题描述

我从以下代码的第二行收到一个段错误:

I am receiving a segfault from the second line of the following code:

FILE *output = NULL;
output = fopen("./output2.txt", "w+");

我不认为这是某种损坏的内存错误，因为当我将 w+ 更改为 r 时.它运行时没有段错误.此外，它似乎是在出现段错误之前创建文件.

I don't think it is some sort of corrupt memory error because when I change w+ to r. It runs with no segfault. ALSO, it appears to create the file right before it segfaults.

结果 mrbatch 是对的

turns out mrbatch is right

我所有的代码供参考:

void writeFile(const char *header, int numRows, int numCols, int **grades, const char  *outFile)
{
    printf("writefile success
");
    int i, j;
    FILE *output = NULL;
    output = fopen("./output2.txt", "w+");  // ERROR HERE (I was wrong, keep reading)
    printf("testestestsetsete


");    //based off the commenters, this code 
                                          //IS reached but is never printed

    fprintf(output, "%s", *header);  //commenters stated error is here
                                     //*header should be header
    fprintf(output, "%d %d
", numRows, numCols); //output the number or rows and columns at the second line

    //output each grades(scores) in the processed 2D array grades
    for(i = 0; i < numRows; i ++ ) {    //loop through all rows
        for( j = 0; j < numCols; j ++ ) //loop through all columns in the i row
        {   
            if( j < numCols - 1 )
                fprintf(output, "%d ", grades[i][j]);
            else
                fprintf(output, "%d
", grades[i][j]);
            //printf(""%d" ", score);
        }
        //printf("
");
    }

    fclose(output); 

}

推荐答案

错误其实是你的fopen之后的第一个fprintf.

The error is actually the first fprintf after your fopen.

fprintf(output, "%s", *header);  //output the same header

%s 格式说明符需要 char * 并且您传递了 char 值(*header)它试图将其解释为地址并导致段错误.

The %s format specifier expects a char * and you passed a char value (*header) which it tried to interpret as an address and caused a segfault.

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