我的程序中出现编译器错误

Question

#include <stdio.h>
#include<stdlib.h>
char push();
char pop();
char display();
char peek();
char reverse();
# define MAX 50
struct stack
    {
        char string[MAX];
        int top= -1;
    };
void main()
    {
        int a;
        printf("Choose an option\n");
        printf("1.Insert\n");
        printf("2.Delete\n");
        printf("3.Display\n");
        printf("4.Peek\n");
        printf("5.Reverse\n");
        scanf("%d", &a);
            switch(a)
                {
                    {
                        case 1: push();
                        break;
                    }
                    {
                        case 2: pop();
                    break;
                    }
                    {
                    case 3: display();
                    break;
                    }
                    {
                    case 4: peek();
                    break;
                    }
                    {
                        case 5: reverse();
                    break;
                    }
                    default : printf("Invalid Input");
                }


    }
char push(char a)
    (
        char a;
        printf("Enter the string");
        scanf("%c",&a);
        if(top=MAX-1)
         {
            printf("Stack Overflow");
         }

        else
         (
         top=top+1;
         string[top]=a;
         )

    )

char pop()
    (
        char c;
        (
            if(top=-1)
            {
                printf("Stack Underflow");
            }
            else(
                c=string[top];
                top=top-1;
                printf("The character removed is %c", c);
                )
           )
     )


char display()
    {
        int i;
        for(i=0,i<=MAX-1,i++)
            {
                printf("%c", string[i]);
            }
    }


char peek()
    (
     printf("The top element is %c", string[top]);
    )


char reverse()
    (
     int i;
     printf("The reverse of string is");
     for(i=MAX-1,i>=0,i--)

        (
         printf("%c",string[i])
         )

     )

这是我的程序，大约一个月前刚刚开始 C 编程。 以下是我的错误。请帮忙。我无法从其他答案中找出答案，如果有人可以纠正我的错误，我会学得更好。谢谢

prog.c:12:16: error: expected ':', ',', ';', '}' or '__attribute__' before '=' token
         int top= -1;
                ^

prog.c:14:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^

prog.c:54:9: error: expected declaration specifiers or '...' before 'printf'
         printf("Enter the string");
         ^

prog.c:55:9: error: expected declaration specifiers or '...' before 'scanf'
         scanf("%c",&a);
         ^

prog.c:56:9: error: expected declaration specifiers or '...' before 'if'
         if(top=MAX-1)
         ^

prog.c:73:13: error: expected identifier or '(' before 'if'
             if(top=-1)
             ^

prog.c:98:6: error: expected declaration specifiers or '...' before 'printf'
      printf("The top element is %c", string[top]);
      ^

prog.c:96:6: error: 'peek' declared as function returning a function
 char peek()
      ^

prog.c:96:6: error: conflicting types for 'peek'

prog.c:6:6: note: previous declaration of 'peek' was here
 char peek();
      ^

prog.c: In function 'peek':

prog.c:105:6: error: expected declaration specifiers or '...' before 'printf'
      printf("The reverse of string is");
      ^

prog.c:106:6: error: expected declaration specifiers or '...' before 'for'
      for(i=MAX-1,i>=0,i--)
      ^

prog.c:112:6: error: expected '{' at end of input
      )
      ^

prog.c:112:6: warning: control reaches end of non-void function [-Wreturn-type]
      )
      ^

Answer 1

struct stack {...};定义了一个类型，即struct stack 。

您不能“初始化”类型，也不能为struct定义默认值。类型的成员，或者您在做时的意图是什么 ... top = -1 .

您可以做的是定义该类型的变量并初始化它:

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


#define STRING_MAX (42)

struct Stack {
  char string[STRING_MAX];
  int top;
}


int main(void) {
  struct Stack stack = {
    "top entry",
    1
  };

  printf("string = '%s', top = %d\n", stack.string, stack.top);

  return EXIT_SUCCESS;
}

上面的例子打印:

string = 'top entry', top = 1