堆栈四则运算

头文件1。

 

#ifndef _TT_H_#define _TT_H_#include<stdio.h>char Precede(char t1,char t2) { char f; switch(t2) { case '+': case '-':if(t1=='('||t1=='#') f= '<'; else f= '>'; break; case '*': case '/':if(t1=='*'||t1=='/'||t1==')') f= '>'; else f= '<'; break; case '(':if(t1==')') printf("error:/n"); else f= '<'; break; case ')':switch(t1) { case '(':f= '='; break; case'#':printf("error/n"); default :f= '>'; } break; case'#':switch(t1) { case'#':f= '='; break; case'(' :printf("error/n"); default :f= '>'; } } return f; } int In(char c) { switch(c) { case'+' : case'-' : case'*' : case'/' : case'(' : case')' : case'#':return 1; default :return 0; } } int Operate(char a,char x,char b) { switch(x) { case'+':return a+b; case'-':return a-b; case'*':return a*b; } return a/b; }#endif

头文件2：

#ifndef _NU_STACK_H#define _NU_STACK_H#include<stdio.h>#define N 20 int nu_stack[N];int nu_top = 0;void nu_push(int c){ nu_stack[nu_top] = c; nu_top++;}int nu_pop(void){ nu_top--; return nu_stack[nu_top];}int nu_is_empty(void){ return nu_top == 0;}int nu_get_top(){ if (nu_top > 0) return nu_stack[nu_top-1]; elsereturn 0;}#endif

头文件3：

#ifndef _CH_STACK_H#define _CHSTACK_H#include<stdio.h>#define Y 20 char ch_stack[Y];int ch_top = 0;void ch_push(char c){ ch_stack[ch_top] = c; ch_top++;}char ch_pop(void){ if(ch_top != 0) {ch_top--; return ch_stack[ch_top]; } elsereturn 0;}int ch_is_empty(void){ return ch_top == 0;}int ch_get_top(){ if (ch_top > 0) return ch_stack[ch_top-1]; elsereturn 0;}#endif

 

man：

#include<stdio.h>#include"nu_stack.h"#include"ch_stack.h"#include"tt.h"#define N 20int expression(char *p) { char a,b,c,x; int i= 0; ch_push('#'); c=p[i++]; x=ch_get_top(); while(c!='#'||x!='#') { if(In(c)) switch(Precede(x,c)) { case'<' :ch_push(c); c=p[i++]; break; case'=' :x=ch_pop(); c=p[i++]; break; case'>' :x = ch_pop(); b = nu_pop(); a = nu_pop(); nu_push(Operate(a,x,b)); } else if(c>='0'&&c<='9') { nu_push(c-48); c = p[i++]; } else printf("error!/n"); x = ch_get_top(); } x = nu_pop(); if(!nu_is_empty()) printf("error !!!/n"); printf("x = %d/n", x); }int main(void) { int i; char str[N]; for( i = 0; i < N; i++ ) { scanf("%c",&str[i]); if(str[i] == '/n') { str[i]='#'; break; } } expression(str); }