做题太慌张了。总是出问题。感觉时间不够用，着急反而效率更低，没有之前不忙不急的时候做的事情更多。

这道题整半天也没做上来，

静下心来写了半小时就差不多了

自己新写的

 1 #include<stdio.h>
 2 int count(char d,int b,int sum){
 3     switch(d){
 4         case '+':
 5             sum=sum+b;
 6             break;
 7         case '-':
 8             sum=sum-b;
 9             break;
10         case '*':
11             sum=sum*b;
12             break;
13         case '/':
14             sum=sum/b;
15             break;
16         default:{
17             return sum;
18             break;
19         }
20     }
21     return sum;
22 }
23 int main(){
24    char c;
25    char d='?';
26    int a;
27    int b=0;
28    int sum;
29    scanf("%d",&sum);
30    //printf("sum==%d\n",sum);
31    c=getchar();
32     
33    while(c!='='){  //printf("c==%c\n",c);
34        if(c=='+'){
35            sum=count(d,b,sum);
36            b=0;
37            d=c;
38                c=getchar();
39        }
40     else if(c=='-'){
41         sum=count(d,b,sum);
42            b=0;
43            d=c;
44                c=getchar();
45     }
46     else if(c=='*'){
47 sum=count(d,b,sum);
48            b=0;
49            d=c;
50                c=getchar();
51         
52     }
53     else if(c=='/'){
54     sum=count(d,b,sum);
55            b=0;
56            d=c;
57                c=getchar();
58     }
59     else {       
60         
61             //printf("c==%c\n",c);
62         a=c-'0';
63         b=b*10+a;//收集数字 
64         //printf("a==%d\n",a);
65         //printf("b==%d\n",b);
66             //printf("sum==%d\n",sum);
67                 c=getchar();
68     }
69 
70    }
71    
72        //printf("END     sum==%d\n",sum);
73 sum=count(d,b,sum);
74       //printf("END     c==%c\n",c);
75             //printf("END     b==%c\n",b);
76        //printf("END     sum==%d\n",sum);
77 sum=count(c,b,sum);
78 printf("%d",sum);
79     return 0;
80     
81     
82 }