-
Notifications
You must be signed in to change notification settings - Fork 0
/
arithmetic.c
73 lines (61 loc) · 2.55 KB
/
arithmetic.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
#include <stdio.h>
#include <ctype.h>
//main function: special calculator
int main() {
char operator; //store operator input
float number; //store number input
float ans; //temporary answer holder
printf("Please enter an arithmetic expression using * and / only: \n");
//a valid input should start with a number,
//and then an opeartor(either * or /) and a number,
//and follow the same pattern (operator, then number).
//read in the first number input, and store in the answer variable
//if there is no input at all, report malformed error message
if (scanf("%f", &number) == -1) {
printf("malformed expression\n");
return 1;
}
else {
ans = number;
}
//use scanf to read in the operator / number input
//a valid opeartor input should be a char type
//a valid number input should be a float type
//use inputcount to keep track of valid inputs
//inputcount should return 2 when inputs are valid
int inputcount = scanf(" %c %f", &operator, &number);
//run the calculator when there is input
while (inputcount != -1) {
//if inputs are valid
if (inputcount == 2) {
//switch cases for operator * and /
switch(operator) {
case '*':
ans = ans * number;
break;
case '/':
if (number == 0) {
//report zero-division error message
printf("division by zero\n");
return 2;
}
else {
ans = ans / number;
}
break;
default://all other operators are not valid in this program
printf("malformed expression\n");
return 1;
}
else {
//report malformed error message when input is not valid
printf("malformed expression\n");
return 1;
}
//read in the next group of operator and number, if any
inputcount = scanf(" %c %f", &operator, &number);
}
//output the answer
printf("%f\n", ans);
return 0;
}