# How to Work with Variables, Data Types, and Arithmetic Expressions in the C Programming Language

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This chapter is from the book

## Exercises

1. Type in and run the five programs presented in this chapter. Compare the output produced by each program with the output presented after each program in the text.
2. Which of the following are invalid variable names? Why?

```Int            char     6_05
Calloc         Xx       alpha_beta_routine
floating       _1312    z
ReInitialize   _        A\$```
3. Which of the following are invalid constants? Why?

```123.456     0x10.5     0X0G1
0001        0xFFFF     123L
0Xab05      0L         -597.25
123.5e2     .0001      +12
98.6F       98.7U     17777s
0996        -12E-12   07777
1234uL      1.2Fe-7   15,000
1.234L      197u      100U
0XABCDEFL   0xabcu    +123```
4. Write a program that converts 27° from degrees Fahrenheit (F) to degrees Celsius (C) using the following formula:

C = (F - 32) / 1.8

5. What output would you expect from the following program?

```#include <stdio.h>

int main (void)
{
char c, d;

c = 'd';
d = c;
printf ("d = %c\n", d);

return 0;
}```
6. Write a program to evaluate the polynomial shown here:

`3x`3` - 5x`2` + 6`

for x = 2.55.

7. Write a program that evaluates the following expression and displays the results (remember to use exponential format to display the result):

`(3.31 x 10`-8` x  2.01 x 10`-7`) / (7.16 x 10`-6` + 2.01 x 10`-8`)`
8. To round off an integer i to the next largest even multiple of another integer j, the following formula can be used:

`Next_multiple = i + j - i % j`

For example, to round off 256 days to the next largest number of days evenly divisible by a week, values of i = 256 and j = 7 can be substituted into the preceding formula as follows:

```Next_multiple    = 256 + 7 - 256 % 7
= 256 + 7 - 4
= 259```
9. Write a program to find the next largest even multiple for the following values of i and j:

 i j 365 7 12,258 23 996 4