[Bài tập]:Day 6:Exercise fuction

Bài 1: Write a C program that accepts a number and square the number with the help of a function.

int square(int x);

           

int square(int x){

            int c=x*x;

            return c;

            }

           

int main(int argc, char *argv[]) {

            int a,b;

           

            printf("Xin moi nhap so : ");

            scanf("%d",&a);

           

            int c=square(a);

            printf("\nLuy thua cua %d la %d",a,c);

            return 0;

Bài 2:2. Write a C program to find the area and perimeter of a circle.

Function prototype: float areaCircle(float radius);

Function prototype: float perimeterCircle(float radius);

Using the library: “Math.h” => PI = 3.14

float area(int x);

float pri(int y);

float area(int x){

            float s=2*3.14*x*x;

            return s;

}

float pri(int y){

            float c=3.14*y*y;

            return c;

}

int main(int argc, char *argv[]) {

            int a;

            printf("Xin moi nhap ban kinh: ");

            scanf("%d",&a);

            float S=area(a);

            printf("\nDien tich hinh tron la: %.2f",S);

            float C=pri(a);

            printf("\nChu vi hinh tron la: %.2f",C);

Bài 3:3. Write a C program to calculate the factorial of an integer

Function prototype:  long factorial(int number);

long factorial(int number);

long factorial(int number){

            int x;

            int fac=1;

            for(x=1;x<=number;x++){

                        fac=fac*x;

            }

            return fac;

}

int main(int argc, char *argv[]) {

            int i,z;

           

            printf("Xin moi nhap so: ");

            scanf("%d",&i);

            z=factorial(i);

            printf("Giai thua cua %d la %d",i,z);

           

            return 0;