为什么从函数返回数组时会收到警告？

Question

我已经看到了一些从stackoverflow上的函数返回数组的例子.我按照这些例子,但我仍然收到警告.

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

char * getNum();

int main(){

    int * num;
    int * i;

    num = getNum();
    puts(num);

    return 0;
}

char * getNum(){

    FILE * fp;
    fp = fopen("number", "r");      //getting a 1000 digit number from a file
    char * n;                       //putting it in "array"
    n = (char *)malloc(1000 * sizeof(char));
    char x[100];
    int i, j = 0;

    while(!feof(fp)){
        fgets(x, 100, fp);
        for(i=0; i<50; i++){        //getting the first 50 characters in a line
            n[j] = x[i];            //to avoid "new line"
            j++;
        }
    }
    fclose(fp);
    n[1000] = '\0';

    return n;
}

puts(num)如果我忽略警告,给出正确的号码？他们为什么会出现？我希望这不算是重复.

cc     8.c   -o 8
8.c: In function ‘main’:
8.c:11:9: warning: assignment from incompatible pointer type
     num = getNum();
         ^
8.c:12:10: warning: passing argument 1 of ‘puts’ from incompatible pointer type
     puts(num);
          ^
In file included from 8.c:1:0:
/usr/include/stdio.h:695:12: note: expected ‘const char *’ but argument is of type ‘int *’
 extern int puts (const char *__s);
            ^

Answer 1

问题是你似乎正在将调用的结果getNum赋给一个类型的变量int *,这在getNum返回a时没有多大意义char *.

您还尝试使用puts该类型的变量进行打印int *,同时puts仅接受a const char *.

更重要的是,你已经超出了函数代码的界限,正如我在评论中已经提到的那样:n = (char *)malloc(1000 * sizeof(char));为1000个字符分配内存.n[1000] = '\0';尝试访问第1001个(!)字符.请记住,数组索引从零开始!