错误：“一元*'的无效类型参数（有'廉政'） [英] error: invalid type argument of ‘unary *’ (have ‘int’)

问题描述

我有一个C程序：

#include <stdio.h>
int main(){
  int b = 10;             //assign the integer 10 to variable 'b'

  int *a;                 //declare a pointer to an integer 'a'

  a=(int *)&b;            //Get the memory location of variable 'b' cast it
                          //to an int pointer and assign it to pointer 'a'

  int *c;                 //declare a pointer to an integer 'c'

  c=(int *)&a;            //Get the memory location of variable 'a' which is
                          //a pointer to 'b'.  Cast that to an int pointer 
                          //and assign it to pointer 'c'.

  printf("%d",(**c));     //ERROR HAPPENS HERE.  

  return 0;
}    

编译器产生一个错误：

Compiler produces an error:

error: invalid type argument of ‘unary *’ (have ‘int’)

有人能解释一下这个错误意味着什么？

Can someone explain what this error means?

推荐答案

由于 C 持有整数指针的地址，它的类型应该是 INT ** ：

Since c is holding the address of an integer pointer, its type should be int**:

int **c;
c = &a;

整个程序就变成了：

The entire program becomes:

#include <stdio.h>                                                              
int main(){
    int b=10;
    int *a;
    a=&b;
    int **c;
    c=&a;
    printf("%d",(**c));   //successfully prints 10
    return 0;
}

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