Examples of function declarations, definitions, and use

[sourcecode language=’cpp’]

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#include

/* Examples of declarations of functions */

void square1(void); /* Example of a function without input parameters

and without return value */

void square2(int i); /* Example of a function with one input parameter

and without return value */

int square3(void); /* Example of a function without input parameters

and with integer return value */

int square4(int i); /* Example of a function with one input parameter

and with integer return value */

int area(int b, int h); /* Example of a function with two input parameters

and with integer return value */

/* Main program: Using the various functions */

int main (void) {

square1(); /* Calling the square1 function */

square2(7); /* Calling the square2 function using 7 as actual

parameter corresponding to the formal parameter i */

printf(“The value of square3() is %d\n”, square3()); /* Ysing the square3

function */

printf(“The value of square4(5) is %d\n”, square4(5)); /* Using the square4

function with 5 as actual parameter corresponding to i */

printf(“The value of area(3,7) is %d\n”, area(3,7)); /* Using the area

function with 3, 7 as actual parameters corresponding

to b, h respectively */

}

/* Definitions of the functions */

/* Function that reads from standard input an integer and prints

it out together with its sum */

void square1(void){

int x;

printf(“Please enter an integer > “);

scanf(“%d”, &x);

printf(“The square of %d is %d\n”, x, x*x);

}

/* Function that prints i together with its sum */

void square2(int i){

printf(“The square of %d is %d\n”, i, i*i);

}

/* Function that reads from standard input an integer and returns

its square */

int square3(void){

int x;

printf(“Please enter an integer > “);

scanf(“%d”, &x);

return (x*x);

}

/* Function that returns the square of i */

int square4(int i){

return (i*i);

}

/* Function that returns the area of the rectangle with base b

and hight h */

int area(int b, int h){

return (b*h);

}

/* The output of this program is:

Please enter an integer > 3

The square of 3 is 9

The square of 7 is 49

Please enter an integer > 4

The value of square3() is 16

The value of square4(5) is 25

The value of area(3,7) is 21

*/[/sourcecode]