C中的后綴運行時錯誤的中綴

Question

這是我編寫的將infix表達式轉換為postfix表達式而不使用c語言結構的代碼。但是有時它會產生意外的輸出，有時會顯示“ segmentation fault”錯誤。此代碼中的錯誤是什么？

#include<stdio.h>
#define size 50
int top=-1;
char s[size];
void push(char ch){
    s[++top] = ch;
}
char pop(){
    char ch = s[top--];return ch;
}
int pr(char elem)
    {                 
        switch(elem)
        {
        case '#': return 0;
        case '(': return 1;
        case '+':
        case '-': return 2;
        case '*':
        case '/': return 3;
        case '^':
        case '$': return 4;
        }
    }

int main(){

    char in[50],post[50],ch,br;
    int i=0,p=0;
    printf("\n\nenter the Infix Expression : ");
        scanf("%s",in);
    push('#');
    while(in[i++] != '\0'){
        ch=in[i];

        if((ch>=48 && ch<=57) || (ch>=65 && ch<=90) || (ch>=97 && ch<=122))
            post[p++] = ch;
        else if(ch == '(')
            push(ch);
        else if(ch == ')'){
            while(s[top] != '(')
                post[p++]=pop();
            br = pop();
        }
        else if(ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '^' || ch == '$'){
            while(pr(s[top]) >= pr(ch))
                post[p++] = pop();                  

            push(ch);      //if priority is less,only push will occur
        }

        //i++;
    }
    while( s[top] != '#')
        post[p++]=pop();
    post[p] = '\0';
    printf("\ninfix : %s \n postfix : %s\n",in,post);
    return 0;
}

Answer 1

這是已調試的代碼。while條件出現錯誤。我正在對其進行更新，然后將其存儲在ch中

#include<stdio.h>
#define size 50
int top=-1;
char s[size];
void push(char ch){
    s[++top] = ch;
}
char pop(){
    char ch = s[top--];return ch;
}
int pr(char br)
    {                 
        switch(br)
        {
        case '#': return 0;
        case '(': return 1;
        case '+':
        case '-': return 2;
        case '*':
        case '/': return 3;
        case '^':
        case '$': return 4;
        }
    }

void main(){

    char in[50],post[50],ch,br;
    int i=0,p=0;
    printf("\n\nenter the Infix Expression : ");
        scanf("%s",in);
    push('#');
    while( (ch=in[i++]) != '\0'){
        if((ch>=48 && ch<=57) || (ch>=65 && ch<=90) || (ch>=97 && ch<=122))
            post[p++] = ch;
        else if(ch == '(')
            push(ch);

        else if(ch == ')'){
            while(s[top] != '(')
                post[p++]=pop();
            br = pop();
        }
        else if(ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '^' || ch == '$'){
            while( pr(s[top]) >= pr(ch) )
          post[p++]=pop();
            push(ch);    //if priority is less,only push will occur
        }

        //i++;
    }
    while( s[top] != '#')
        post[p++]=pop();
    post[p] = '\0';
    printf("\ninfix : %s \n postfix : %s\n",in,post);

}