我正在使用堆栈在 c 中编写一个计算器程序,在下面的程序中,我使用了中缀到后缀转换和下一个后缀评估的概念。我得到 1+2 答案的正确答案是 3,但对于 11+1 或任何两位及以上的数字,我得到的答案是错误的。
谁能帮助我我将在我的代码中包含的内容,以便它适用于超过两位数,如 28+25 或任何数字?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define SIZE 50 /* Size of Stack */
int top = -1;
char pofx[50];
char s[SIZE];
int infix_to_postfix() {
char infx[50], ch;
int i = 0, k = 0;
void push(char elem) { /* Function for PUSH operation */
s[++top] = elem;
}
char pop() { /* Function for POP operation */
return (s[top--]);
}
int pr(char elem) { /* Function for precedence */
switch (elem) {
case '#':
return 0;
case '(':
return 1;
case '+':
case '-':
return 2;
case '*':
case '/':
return 3;
}
return -1;
}
printf("\n\nEnter a Value to calculate : ");
gets(infx);
push('#');
while ((ch = infx[i++]) != '\0') {
if (ch == '(') push(ch);
else if (isalnum(ch)) pofx[k++] = ch;
else if (ch == ')') {
while (s[top] != '(')
pofx[k++] = pop();
char elem = pop(); /* Remove ( */
} else { /* Operator */
while (pr(s[top]) >= pr(ch))
pofx[k++] = pop();
push(ch);
}
}
while (s[top] != '#') /* Pop from stack till empty */
pofx[k++] = pop();
pofx[k] = '\0'; /* Make pofx as valid string */
printf("\n\nGiven Infix Expn: %s Postfix Expn: %s\n", infx, pofx);
return (int) pofx[k];
}
void postfix_evaluate() {
char ch;
int i = 0, op1, op2;
void pushit(int elem) { /* Function for PUSH operation */
s[++top] = elem;
}
int popit() { /* Function for POP operation */
return (s[top--]);
}
infix_to_postfix();
while ((ch = pofx[i++]) != '\0') {
if (isdigit(ch)) pushit(ch - '0'); /* Push the operand */
else { /* Operator,pop two operands */
op2 = popit();
op1 = popit();
switch (ch) {
case '+':
pushit(op1 + op2);
break;
case '-':
pushit(op1 - op2);
break;
case '*':
pushit(op1 * op2);
break;
case '/':
pushit(op1 / op2);
break;
}
}
}
printf("\n Given Postfix Expn: %s\n", pofx);
printf("\n Result after Evaluation: %d\n", s[top]);
}
int main() {
postfix_evaluate();
return 0;
}