C 언어 수업 설계 의 계산기 기능

/*===============================================*\
**     ：     ，    10*(20.2-30.6)+5.0/2     
**     ：        （   ）
** IDE：Dev-Cpp 4.9.9.2
**     ：           
**   ： 2014-6-17
\*===============================================*/
 
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define maxn 1000
char buf[maxn], str[maxn], signStack[maxn], ch[2];
int len, id, idSign, idAns, i, n;
double ans[maxn];
 
void checkSign(char sign){
 if(sign == '(') signStack[idSign++] = sign;
 else if(sign == '*' || sign == '/'){
 while(idSign && (signStack[idSign-1] == '*' || signStack[idSign-1] == '/'))
 str[id++] = signStack[--idSign];
 signStack[idSign++] = sign;
 }else if(sign == ')'){
 while(signStack[idSign-1] != '(') str[id++] = signStack[--idSign];
 --idSign;
 }else{
 while(idSign && signStack[idSign-1] != '(') str[id++] = signStack[--idSign];
 signStack[idSign++] = sign;
 }
 str[id++] = ' ';
}
 
int check(double a, char sign){
 if(a == 0 && sign == '/'){
 printf("     0!，    。
");
 system("pause");
 exit(EXIT_FAILURE);
 }
 return 1;
}
 
double cal(double a, double b, char sign){
 switch(sign){
 case '+': return a + b;
 case '-': return a - b;
 case '*': return a * b;
 case '/': return a / b;
 }
}
 
int main(){ 
 
 printf("\t\t\t\t     

");
 printf("\t\t ======================================
");
 printf("\t\t ||   + - * / ( )          ||
");
 printf("\t\t ======================================
");
 printf("\t\t\t\t\t\t    ：   
");
 printf("\t\t\t\t\t\t    ：2014 6 17 
");
 printf("\t\t\t\t\t\tEmail：[email protected]
");
 
 printf("        ，  -10*(20.2-30.6)+5.0/2
     :
"); 
 do{
 gets(buf); id = idSign = idAns = 0;
 if((len = strlen(buf)) == 0) continue;
 
 int flag = 0; //       '-'          。1    ，0   +*/(
 /*    ：          -，       ，        +*-/(  
       ，              */
 
 for(i = 0; i < len; ++i){
 if(buf[i] == ' ') continue;
 if(buf[i] >= '0' && buf[i] <= '9' || buf[i] == '.' || buf[i] == '-' && !flag){
 str[id++] = buf[i]; flag = 1;
 }
 else { 
 str[id++] = ' '; checkSign(buf[i]); 
 if(buf[i] != ')') flag = 0;
 else flag = 1;
 }
 }
 while(idSign) str[id++] = signStack[--idSign];
 
 for(i = 0, n = 0; i < id; ++i){
 if(str[i] == ' ') continue;
 /*          ‘-'         ， ‘-'          ，       */
 if(str[i] >= '0' && str[i] <= '9' || str[i] == '.' || str[i] == '-' 
 && (str[i+1] >= '0' && str[i+1] <= '9' || str[i+1] == '.')){
 sscanf(str + i, "%lf%n", &ans[idAns++], &n);
 i += n - 1; continue;
 }else if(check(ans[idAns-1], str[i])){
 ans[idAns-2] = cal(ans[idAns-2], ans[idAns-1], str[i]);
 --idAns; 
 }
 }
 printf("    %.2lf
", ans[0]);
 printf("  Y   , N   : ");
 scanf("%s", ch);
 }while(ch[0] == 'Y' || ch[0] == 'y');
 printf("      ！  
");
 system("pause");
 return 0;
}