C: Procedural abstraction using arrays

The initial program does not use much abstraction.

The following program uses an array to represent all the needed string variables. In C, a string is represented by an array of characters. So the program uses a 2D array. The offset index into the array is the string variable used. In the following program, no constants (or pseudo-constants) are used, just literal values. This approach will be improved in the following programs using straight-forward abstraction techniques - the main objective of this progression.

Compare this program with the programs developed in Lua: Procedural abstraction using variables .

The following correspondence is used.

Element data1[0] represents the text for NAME.

Element data1[1] represents the text for SIZE.

Element data1[2] represents the text for ANIMAL.

Element data1[3] represents the text for FUR.

Element data1[4] represents the text for COLOR.

Element data1[5] represents the text for OBJECT.

Note that this is the way that, internally, the run-time system of a compiled program handles local variables allocated on the stack - by the offset of the variable into memory. Here is the C code [#1]

#include <stdio.h>
int main() {
	// declarations
	int show1;
	char data1[6][256];
	// input
	scanf("%s",data1[0]);
	scanf("%s",data1[1]);
	scanf("%s",data1[2]);
	scanf("%s",data1[3]);
	scanf("%s",data1[4]);
	scanf("%s",data1[5]);
	// process
	// output
	printf("\t%s had a %s %s,\n",data1[0],data1[1],data1[2]);
	printf("\t%s %s, %s %s\n",data1[1],data1[2],data1[1],data1[2]);
	printf("\t%s had a %s %s,\n",data1[0],data1[1],data1[2]);
	printf("\tit's %s was %s as %s.\n",data1[3],data1[4],data1[5]);
	printf("\n");
	printf("\tAnd everywhere that %s went,\n",data1[0]);
	printf("\t%s went, %s went.\n",data1[0],data1[0]);
	printf("\tEverywhere that %s went,\n",data1[0]);
	printf("\tthe %s was sure to go.\n",data1[2]);
	return 0;
	}

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

Here is an example input.

Mary
little
lamb
fleece
white
snow

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

	Mary had a little lamb,
	little lamb, little lamb
	Mary had a little lamb,
	it's fleece was white as snow.
	And everywhere that Mary went,
	Mary went, Mary went.
	Everywhere that Mary went,
	the lamb was sure to go.

Here is an example input.

Johnny
tiny
pig
hide
black
coal

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

	Johnny had a tiny pig,
	tiny pig, tiny pig
	Johnny had a tiny pig,
	it's hide was black as coal.
	And everywhere that Johnny went,
	Johnny went, Johnny went.
	Everywhere that Johnny went,
	the pig was sure to go.

Here is an example input.

Susan
hopping
rabbit
fur
brown
earth

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

	Susan had a hopping rabbit,
	hopping rabbit, hopping rabbit
	Susan had a hopping rabbit,
	it's fur was brown as earth.
	And everywhere that Susan went,
	Susan went, Susan went.
	Everywhere that Susan went,
	the rabbit was sure to go.

Let us now perform some procedural abstraction to the above program.

All input will be done by the function inputGet1. (always changes variables)
All processing will be done by the function processDo1. (usually changes some variables)
All output will be done by the function outputPut1. (should not change variables)

Note: For this simple example, there is no significant processing part but that part is still included. Note the use of the define for the abstracted literals (as previously covered). This results in the following correspondence.

Element data1[RS_NAME] represents the text for NAME.

Element data1[RS_SIZE] represents the text for SIZE.

Element data1[RS_ANIMAL] represents the text for ANIMAL.

Element data1[RS_FUR] represents the text for FUR.

Element data1[RS_COLOR] represents the text for COLOR.

Element data1[RS_OBJECT] represents the text for OBJECT.

Here is the C code [#2]

#include <stdio.h>
// global defines
#define RS_NAME 0
#define RS_SIZE 1
#define RS_ANIMAL 2
#define RS_FUR 3
#define RS_COLOR 4
#define RS_OBJECT 5
#define RS_DMAX 6
#define RS_SMAX 256
void inputGet1(char data2[RS_DMAX][RS_SMAX]) {
	scanf("%s",data2[RS_NAME]);
	scanf("%s",data2[RS_SIZE]);
	scanf("%s",data2[RS_ANIMAL]);
	scanf("%s",data2[RS_FUR]);
	scanf("%s",data2[RS_COLOR]);
	scanf("%s",data2[RS_OBJECT]);
	}
void processDo1(char data3[RS_DMAX][RS_SMAX]) {
	}
void outputPut1(char data4[RS_DMAX][RS_SMAX]) {
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s %s, %s %s\n",data4[RS_SIZE],data4[RS_ANIMAL],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\tit's %s was %s as %s.\n",data4[RS_FUR],data4[RS_COLOR],data4[RS_OBJECT]);
	printf("\n");
	printf("\tAnd everywhere that %s went,\n",data4[RS_NAME]);
	printf("\t%s went, %s went.\n",data4[RS_NAME],data4[RS_NAME]);
	printf("\tEverywhere that %s went,\n",data4[RS_NAME]);
	printf("\tthe %s was sure to go.\n",data4[RS_ANIMAL]);
	}
int main() {
	// declarations
	char data1[RS_DMAX][RS_SMAX];
	// input
	inputGet1(data1);
	// process
	processDo1(data1);
	// output
	outputPut1(data1);
	return 0;
	}

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

Here is an example input.

Mary
little
lamb
fleece
white
snow

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

	Mary had a little lamb,
	little lamb, little lamb
	Mary had a little lamb,
	it's fleece was white as snow.
	And everywhere that Mary went,
	Mary went, Mary went.
	Everywhere that Mary went,
	the lamb was sure to go.

Here is an example input.

Johnny
tiny
pig
hide
black
coal

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

	Johnny had a tiny pig,
	tiny pig, tiny pig
	Johnny had a tiny pig,
	it's hide was black as coal.
	And everywhere that Johnny went,
	Johnny went, Johnny went.
	Everywhere that Johnny went,
	the pig was sure to go.

Here is an example input.

Susan
hopping
rabbit
fur
brown
earth

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

	Susan had a hopping rabbit,
	hopping rabbit, hopping rabbit
	Susan had a hopping rabbit,
	it's fur was brown as earth.
	And everywhere that Susan went,
	Susan went, Susan went.
	Everywhere that Susan went,
	the rabbit was sure to go.

There is a common repeated pattern in the input statements in inputGet1.

This pattern is abstracted in the following program by introducing the inputGet2 function. Here is the C code [#3]

#include <stdio.h>
// global defines
#define RS_NAME 0
#define RS_SIZE 1
#define RS_ANIMAL 2
#define RS_FUR 3
#define RS_COLOR 4
#define RS_OBJECT 5
#define RS_DMAX 6
#define RS_SMAX 256
void inputGet2(char *prompt1, char *var1) {
	scanf("%s",var1);
	}
void inputGet1(char data2[RS_DMAX][RS_SMAX]) {
	inputGet2("Name",data2[RS_NAME]);
	inputGet2("Size",data2[RS_SIZE]);
	inputGet2("Animal",data2[RS_ANIMAL]);
	inputGet2("Fur",data2[RS_FUR]);
	inputGet2("Color",data2[RS_COLOR]);
	inputGet2("Object",data2[RS_OBJECT]);
	}
void processDo1(char data3[RS_DMAX][RS_SMAX]) {
	}
void outputPut1(char data4[RS_DMAX][RS_SMAX]) {
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s %s, %s %s\n",data4[RS_SIZE],data4[RS_ANIMAL],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\tit's %s was %s as %s.\n",data4[RS_FUR],data4[RS_COLOR],data4[RS_OBJECT]);
	printf("\n");
	printf("\tAnd everywhere that %s went,\n",data4[RS_NAME]);
	printf("\t%s went, %s went.\n",data4[RS_NAME],data4[RS_NAME]);
	printf("\tEverywhere that %s went,\n",data4[RS_NAME]);
	printf("\tthe %s was sure to go.\n",data4[RS_ANIMAL]);
	}
int main() {
	// declarations
	char data1[RS_DMAX][RS_SMAX];
	// input
	inputGet1(data1);
	// process
	processDo1(data1);
	// output
	outputPut1(data1);
	return 0;
	}

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

Here is an example input.

Mary
little
lamb
fleece
white
snow

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

	Mary had a little lamb,
	little lamb, little lamb
	Mary had a little lamb,
	it's fleece was white as snow.
	And everywhere that Mary went,
	Mary went, Mary went.
	Everywhere that Mary went,
	the lamb was sure to go.

Here is an example input.

Johnny
tiny
pig
hide
black
coal

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

	Johnny had a tiny pig,
	tiny pig, tiny pig
	Johnny had a tiny pig,
	it's hide was black as coal.
	And everywhere that Johnny went,
	Johnny went, Johnny went.
	Everywhere that Johnny went,
	the pig was sure to go.

Here is an example input.

Susan
hopping
rabbit
fur
brown
earth

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

	Susan had a hopping rabbit,
	hopping rabbit, hopping rabbit
	Susan had a hopping rabbit,
	it's fur was brown as earth.
	And everywhere that Susan went,
	Susan went, Susan went.
	Everywhere that Susan went,
	the rabbit was sure to go.

We can improve our code by going from code-driven programming to data-driven programming. This is done with the use of a constant literal array called NAMES1 - all uppercase since it is a constant (a named literal).

char* NAMES1[RS_DMAX] = {"Name","Size","Animal","Fur","Color","Object"};

This results in the following correspondence.

Element NAMES1[RS_NAME] represents the text "Name".

Element NAMES1[RS_SIZE] represents the text "Size".

Element NAMES1[RS_ANIMAL] represents the text "Animal".

Element NAMES1[RS_FUR] represents the text "Fur".

Element NAMES1[RS_COLOR] represents the text "Color".

Element NAMES1[RS_OBJECT] represents the text "Object".

The use of NAMES1 allows the literal text to be abstracted to one place - the constant literal array NAMES1. Here is the C code [#4]

#include <stdio.h>
// global defines
#define RS_NAME 0
#define RS_SIZE 1
#define RS_ANIMAL 2
#define RS_FUR 3
#define RS_COLOR 4
#define RS_OBJECT 5
#define RS_DMAX 6
#define RS_SMAX 256
char* NAMES1[RS_DMAX] = {"Name","Size","Animal","Fur","Color","Object"};
void inputGet2(char *prompt1, char *var1) {
	scanf("%s",var1);
	}
void inputGet1(char data2[RS_DMAX][RS_SMAX]) {
	for (int pos1=0; pos1<RS_DMAX; pos1++) {
		inputGet2(NAMES1[pos1],data2[pos1]);
		}
	}
void processDo1(char data3[RS_DMAX][RS_SMAX]) {
	}
void outputPut1(char data4[RS_DMAX][RS_SMAX]) {
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s %s, %s %s\n",data4[RS_SIZE],data4[RS_ANIMAL],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\t%s had a %s %s,\n",data4[RS_NAME],data4[RS_SIZE],data4[RS_ANIMAL]);
	printf("\tit's %s was %s as %s.\n",data4[RS_FUR],data4[RS_COLOR],data4[RS_OBJECT]);
	printf("\n");
	printf("\tAnd everywhere that %s went,\n",data4[RS_NAME]);
	printf("\t%s went, %s went.\n",data4[RS_NAME],data4[RS_NAME]);
	printf("\tEverywhere that %s went,\n",data4[RS_NAME]);
	printf("\tthe %s was sure to go.\n",data4[RS_ANIMAL]);
	}
int main() {
	// declarations
	char data1[RS_DMAX][RS_SMAX];
	// input
	inputGet1(data1);
	// process
	processDo1(data1);
	// output
	outputPut1(data1);
	return 0;
	}

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

Here is an example input.

Mary
little
lamb
fleece
white
snow

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

	Mary had a little lamb,
	little lamb, little lamb
	Mary had a little lamb,
	it's fleece was white as snow.
	And everywhere that Mary went,
	Mary went, Mary went.
	Everywhere that Mary went,
	the lamb was sure to go.

Here is an example input.

Johnny
tiny
pig
hide
black
coal

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

	Johnny had a tiny pig,
	tiny pig, tiny pig
	Johnny had a tiny pig,
	it's hide was black as coal.
	And everywhere that Johnny went,
	Johnny went, Johnny went.
	Everywhere that Johnny went,
	the pig was sure to go.

Here is an example input.

Susan
hopping
rabbit
fur
brown
earth

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

	Susan had a hopping rabbit,
	hopping rabbit, hopping rabbit
	Susan had a hopping rabbit,
	it's fur was brown as earth.
	And everywhere that Susan went,
	Susan went, Susan went.
	Everywhere that Susan went,
	the rabbit was sure to go.