C: If examples and refactoring

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The following code gets an integer value for x and prints out whether x is nonnegative or negative.

Here is the C code.

#include <stdio.h>

int main() {
	// declarations
	int x1;
	// input
	printf("Enter an integer value for x.\n");
	scanf("%d",&x1);
	printf("You entered %d for x.\n",x1);
	// process - none
	// output
	printf("\n");
	if (x1 >= 0) {
		printf("The value %d is nonnegative.\n",x1);
		}
	else {
		printf("The value %d is negative.\n",x1);
		}
	return 0;
	}

Here are some examples of input and output for the above program code.

Here is an example input.

23

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 23 for x.

The value 23 is nonnegative.

Here is an example input.

-45

For the above example input, here is the expected output.

Enter an integer value for x.
You entered -45 for x.

The value -45 is negative.

Here is an example input.

0

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 0 for x.

The value 0 is nonnegative.

Note the following.

The physical/programmer view of the code uses variable name x1 to represent logical/user concept of x.
The logical/user view of the code uses logical name x. The user has no idea that internally the physical code uses x1.

In software development/engineering, the term refactoring refers to rewriting code to be better, in some way, but that does the same thing.

Below is a program that does the same thing as the above program but removes some redundancy in the output statements. Verify to yourself that the code does the same thing and that you understand how the if statement flow works. Here is the C code.

#include <stdio.h>

int main() {
	// declarations
	int x1;
	// input
	printf("Enter an integer value for x.\n");
	scanf("%d",&x1);
	printf("You entered %d for x.\n",x1);
	// process - none
	// output
	printf("\n");
	printf("The value %d is ",x1);
	if (x1 >= 0) {
		printf("nonnegative");
		}
	else {
		printf("negative");
		}
	printf(".\n");
	return 0;
	}

Here are some examples of input and output for the above program code.

Here is an example input.

23

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 23 for x.

The value 23 is nonnegative.

Here is an example input.

-45

For the above example input, here is the expected output.

Enter an integer value for x.
You entered -45 for x.

The value -45 is negative.

Here is an example input.

0

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 0 for x.

The value 0 is nonnegative.

Now study the refactored code below and assure yourself that you understand how it works. Here is the C code.

#include <stdio.h>

int main() {
	// declarations
	int x1;
	// input
	printf("Enter an integer value for x.\n");
	scanf("%d",&x1);
	printf("You entered %d for x.\n",x1);
	// process - none
	// output
	printf("\n");
	printf("The value %d is ",x1);
	if (x1 >= 0) {
		printf("non");
		}
	printf("negative.\n");
	return 0;
	}

Here are some examples of input and output for the above program code.

Here is an example input.

23

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 23 for x.

The value 23 is nonnegative.

Here is an example input.

-45

For the above example input, here is the expected output.

Enter an integer value for x.
You entered -45 for x.

The value -45 is negative.

Here is an example input.

0

For the above example input, here is the expected output.

Enter an integer value for x.
You entered 0 for x.

The value 0 is nonnegative.

The first program is considered the easiest to understand (for a programmer) but has more redundancy (repetition) of text.

The last program is considered the most to have the lest redundancy (repetition) of text but is not as easy to understand (for the programmer).

In general, the last program is better from a programming point of view.

In general, companies who hire programmers who are not as capable will prefer the first program.

In general, companies who hire better programmers will prefer the first program.

General rule: Removing redundancy in programs makes the programs better but makes them require more time to understand.