如何将'='附加到字符串 [英] How to append '=' to a string

问题描述

我试图在数组末尾添加 = ，然后通过添加0结束它

I am trying to add = at the end of my array and then end it by appending a 0

这就是我分配空间的方式

This is how I allocate my space

char* postExpr = malloc(sizeof(char)*MAX_LEN);

我尝试了很多方法，但是我仍然无法在字符串的末尾添加字符'='，其他所有字符都可以正常工作.

I have tried many methods but I am still failing to append character '=' at the end of my string, every other character works just fine.

我尝试了什么

postExpr[postLen++] = 61;
postExpr[postLen++] = '=';
postExpr[postLen++] = infExpr[i];

在infExpr [i]中

存储值'='

in infExpr[i] is stored the value '='

char* infix2postfix (const char* infExpr) {
    char* postExpr = malloc (sizeof(char)*MAX_LEN);
    if(postExpr == NULL)
        return NULL;
    tStack* s = (tStack*) malloc(sizeof(tStack));
    if(s == NULL)
    {
        free(postExpr);
        return NULL;
    }
    unsigned postLen = 0;
    for(int i = 0; i< MAX_LEN; i++)
    {
        switch(infExpr[i])
        {
            case '*':
            case '/':
            case '+':
            case '-': doOperation(s,infExpr[i],postExpr,&postLen); break;

            case '(': stackPush(s,infExpr[i]); break;
            case ')': untilLeftPar(s,postExpr,&postLen); break;
            case '=': 
            while(!stackEmpty(s))
            {
                stackTop(s,&postExpr[postLen++]);
                stackPop(s);
            }
            postExpr[postLen++] = '='; //NO APPEND HERE!!!
            postExpr[postLen++] = 0;
            postLen = MAX_LEN;
            break;
            case 0:
            postExpr[postLen++] = '=';
            postExpr[postLen++] = 0;
            postLen = MAX_LEN;
            break;
            default: postExpr[postLen++] = infExpr[i];  break;
        }
    }
    return postExpr;
}

推荐答案

问题出在我的堆栈上，我忘了初始化它，因此它将存储值0，该值附加在'='之前，从而使char不可读

The problem was with my stack, I forgot to initializate it, so it would store value 0 which was appended before '=' and thus made the char unreadable

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