ç冲突的类型错误 [英] C conflicting type bug

问题描述

当我尝试编译此我被GCC，我有冲突的类型 pack_cui（C）告诉。

我不明白我怎么可以让冲突的类型，因为我知道我传递一个的char * 。我是新的C，所以我敢肯定，我失去了一些东西明显。

  INT的main（）{
  字符* C =的malloc（sizeof的（字符）* 4）;
  C [0] = 1;
  C [1] = 2;
  C [2] = 1;
  C [3] = 4;
  pack_cui（℃）;
  返回0;
}unsigned int类型pack_cui（字符* C）{
  unsigned int类型new_int = 0;
  无符号整型我;
  对于（I = 0; I＆下; 4;我++）{
    new_int = new_int | （无符号整数）（符号int）C [I]
    如果（ⅰ= 3！）new_int = new_int＆所述;＆下; 8;
  }
  返回new_int;
}
 

我收到的错误是

  hw12.c：17：14：错误：冲突的类型'pack_cui
 unsigned int类型pack_cui（字符* C）{
              ^
hw12.c：13：5：注意：previous的pack_cui'隐式声明在这里
     pack_cui（℃）;
 

解决方案

当你调用一个未声明的功能，C89标准要求隐式声明。该声明将是：

  INT pack_cui（）;
 

的（）是不一样的（无效），该函数接受一个，表示未指定的若干参数，而（无效）表示为零。这是从pre-ISO / ANSI C遗留下来的，早在K＆放大器; R天。

您不希望出现这种情况，因为这是错误的声明。在上面创建自己的声明，上面的main（）：

 无符号pack_cui（字符*）;
 

When I try to compile this I'm being told by gcc that I have conflicting types for pack_cui(C).

I don't see how I could be getting conflicting types as I know I'm passing in a char*. I'm new to C so I'm sure I'm missing something obvious.

int main(){
  char* C = malloc(sizeof(char) * 4);
  C[0] = 1;
  C[1] = 2;
  C[2] = -1;
  C[3] = 4;
  pack_cui(C);
  return 0;
}

unsigned int pack_cui(char* C){
  unsigned int new_int = 0;
  unsigned int i;
  for(i = 0; i < 4; i++){
    new_int = new_int | (unsigned int)(signed int)C[i];
    if(i != 3) new_int = new_int << 8;
  }
  return new_int;
}

The error I received was

hw12.c:17:14: error: conflicting types for ‘pack_cui’
 unsigned int pack_cui(char* C){
              ^
hw12.c:13:5: note: previous implicit declaration of ‘pack_cui’ was here
     pack_cui(C);

解决方案

When you call an undeclared function, the C89 standard mandates an implicit declaration. This declaration would be:

int pack_cui();

The () is not the same as (void), it indicates that the function takes an unspecified number of arguments, whereas (void) means zero. This is left over from pre-ISO/ANSI C, back in the K&R days.

You don't want that, because that is the wrong declaration. Create your own declaration at the top, above main():

unsigned pack_cui(char *);

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