Question

尽管在main（）之前声明了“ getline”和“ copy”函数原型，但我还是遇到了这些错误。该程序直接来自 C编程语言中的代码，因此我不确定问题出在哪里以及如何解决。

#include <stdio.h>

int getline(char line[], int maxline);
void copy(char to[], char from[]);

int main()
{

}

int getline(char s[], int lim)
{
    int c, i;

    for (i=0; i<lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)
        s[i] = c;
    if (c == '\n') {
        s[i] = c;
        ++i;
    }
    s[i] = '\0';
    return i;
}

void copy(char to[], char from[])
{
    int i;

    i = 0;
    while ((to[i] = from[i]) != '\0')
        ++i;
}

编译器产生的确切错误是：

string_reverser.c:4:5: error: conflicting types for 'getline'
 int getline(char line[], int maxline);
     ^~~~~~~

In file included from string_reverser.c:1:0:
c:\mingw\include\stdio.h:650:1: note: previous declaration of 'getline' was here
 getline (char ** __restrict__, size_t * __restrict__, FILE * __restrict__);
 ^~~~~~~

string_reverser.c:27:5: error: conflicting types for 'getline'
 int getline(char s[], int lim)
     ^~~~~~~

In file included from string_reverser.c:1:0:
c:\mingw\include\stdio.h:650:1: note: previous declaration of 'getline' was here
 getline (char ** __restrict__, size_t * __restrict__, FILE * __restrict__);
 ^~~~~~~

Answer 1

POSIX函数getline()现在是一个标准库函数，已经（已经）在<stdio.h>中声明（但是在编写K＆R时不是标准的）。因此，您不能在C语言中重新声明该函数。解决方法是将您的getline函数重命名为其他名称，例如getline_new 使用此变通方法，更新后的代码如下所示，或者您可能希望切换到C ++，以便灵活地具有多个具有相同名称，但参数不同的函数，包括参数类型（多态概念）

    #include <stdio.h>

    int getline_new(char line[], int maxline);
    void copy(char to[], char from[]);

    int main()
    {

    }

    int getline_new(char s[], int lim)
    {
       int c, i;

       for (i=0; i<lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)
        s[i] = c;
       if (c == '\n') {
        s[i] = c;
        ++i;
     }
     s[i] = '\0';
     return i;
    }

   void copy(char to[], char from[])
   {
    int i;

    i = 0;
    while ((to[i] = from[i]) != '\0')
        ++i;
   }

gcc在编译过程中错误“冲突类型”和“先前声明”

1 个答案: