栈的应用——四则表达式

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#include <stdio.h>#define MAX 100struct operand{    int data[MAX];    int top;};struct operator_ch{    int top;    char data[MAX];};typedef struct operand OPND;typedef struct operator_ch OPCH;void init_OPND_stack(OPND *stack){stack->top = -1;}void init_OPCH_stack(OPCH *stack){stack->top = -1;}void is_empty_OPND(OPND *stack){if(stack->top == -1){return -1;}return 0;}void is_empty_OPCH(OPCH *stack){if(stack->top == -1){return -1;}return 0;}int get_OPND_top(OPND *stack){if(is_empty_OPND(stack) == -1){return -1;}return stack->data[stack->top];}int get_OPCH_top(OPCH *stack){if(is_empty_OPCH(stack) == -1){return -1;}return stack->data[stack->top];}int push_OPND(OPND *stack, int num){    stack->data[++(stack->top)] = num;}int push_OPCH(OPND *stack, char ch){    stack->data[++(stack->top)] = ch;}int pop_OPND(OPND *stack){if(is_empty_OPND(stack) == -1){return -1;}    int num = stack->data[stack->top];(stack->top)--;return num;} char pop_OPCH(OPCH *stack){if(is_empty_OPCH(stack) == -1){return -1;}    char ch = stack->data[stack->top];(stack->top)--;return ch;} int get_priority(char ch){if(ch == '+' || ch == '-'){return 1;}if(ch == '*' || ch == '/'){return 2;}}int compare_priority(char op_ch, char ch){if(get_priority(op_ch) > get_priority(ch)){return 1;}return -1;}int count(int num1, int num2, char ch){    int result;switch(ch){case '+':{            result = a + b;break;}case '-':{result = a - b;break;}case '*': 2{result = a * b;break;}case '-':{result = a / b;break;}}return result;}int main(){    char ch;char op_ch;while((ch = getchar()) != '\n'){        if(ch >= '0' && ch <= '9'){            push_stack1();}if(ch == '+' || ch == '-' || ch == '*' || ch == '/'){op_ch = pop_stack2();if(compare(op_ch,ch) > 0){push_stack2(ch);}else{count(a,b,op_ch);}}}return 0;}
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