在 C 中将数组写入文件 [英] Writing an array to a file in C

问题描述

我试图将前 N 个素数的数组写入 txt 文件，每行 5 个条目，每个条目之间有 10 个空格.相关代码如下:

I am attempting to write an array of the first N primes to a txt file in rows of 5 entries each, with 10 spaces between each entry. The relevant code is as follows:

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

#define N 1000

...

void writePrimesToFile(int p[N], char filename[80])
{
    int i;
    FILE *fp = fopen(filename, "w");
    for(i = 0; i<=N-1; i++)
    {
        for(i = 0; i<5; i++)
        {
            fprintf(filename, "%10%i", p[i]);
        }
        printf("/n");
    fclose(fp);
    }


    printf("Writing array of primes to file.\n");
}

编译器抛出以下错误:

primes.c:40:4: warning: passing argument 1 of ‘fprintf’ from incompatible pointer type [enabled by default]
    fprintf(filename, "%10%i", p[i]);
    ^
In file included from /usr/include/stdio.h:29:0,
                 from primes.c:1:
/usr/include/stdio.h:169:5: note: expected ‘struct FILE *’ but argument is of type ‘char *’
 int _EXFUN(fprintf, (FILE *, const char *, ...)
     ^

许多谷歌搜索都没有结果.任何帮助将不胜感激.

Numerous Google searches have not been fruitful. Any help would be much appreciated.

推荐答案

在允许使用 fp 之前测试 fopen() 的输出:

Test the output of fopen() before allowing fp to be used:

FILE *fp = fopen(filename, "w");   
if(fp)//will be null if failed to open
{
    //continue with stuff
    //...    
}

fprintf(...) 的第一个参数也是 文件 *.变化:

Also 1st argument to fprintf(...) is of type FILE *. Change:

fprintf(filename, "%10%i", p[i]);
        ^^^^^^^^

到

fprintf(fp, "%i", p[i]);
        ^^//pointer to FILE struct

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