Class 4: Homework

You must print this sheet out and write/type answers on it!

Below is a short C program.

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <ctype.h>

int main()
{
  char s[10];
  double t = 0.0, x;

  while(fscanf(stdin,"%s",s) == 1)
  {
    if (isdigit(s[0]))
      t += sin(atoi(s));    
  }
  
  fprintf(stdout,"%f\n",t);

  return 0;
}

Given the definitions in main, what is the type of the expression 2*t?
```
	
```
Given the definitions in main, what is the type of the expression &t?
```
	
```
Given the definitions in main, what is the type of the expression s[0]?
```
	
```
Given the definitions in main, what is the type of the expression s?
```
	
```
Given the definitions in main, what is the type of the expression atoi(s)? Hint: The atoi function is defined in the standard C library stdlib.h. Do a man atoi to help answser this question.
```
	
```
This program uses a function isdigit. Do a man isdigit to tell me: a) which .h file do you have to include for isdigit? and b) what does the function isdigit do?
```
	
```

Suppose the function call
```
	  fscanf("%i %i %i",&a,&b,&c);
	
```
returns the value 2. What does that tell you?
```
	
```
Suppose the string
```
char str[6];
	
```
is set to contain the the value "the". write the contents of the array str.