Custom functions in C Language

Custom functions in C Language

In C language, you can use system functions or your own functions, that is, user-defined functions.

There are four types of custom functions

First:

Function Declaration

void sayH();

Function implementation

Void sayH () {printf ("hello ");}

Type 2: parameters without return values

Function declaration:

void pxsbx(int c,int k);

Function implementation:

void pxsbxx(int c,int k){    int i,j;    for (i=0; i<c; i++) {        for (j=0; j<=i; j++) {            printf(" ");        }        for (j=0; j<k; j++) {            if (j==0||j==k-1||i==0||i==c-1) {                printf("*");            }else{                  printf(" ");            }              }        printf("\n");    }}

Function call

Int c, k; printf ("Enter length:"); scanf ("% d", & c); printf ("Enter width :"); scanf ("% d", & k); pxsbxx (c, k );

Running result

3. Parameters and return values

Statement:

int add1(int num1,int num2,int num3);

Implementation

int add1(int num1,int num2,int num3){    int sum=num1+num2+num3;    return sum;}

Call

 int num1,num2,num3,sum;    scanf("%d%d%d",&num1,&num2,&num3);    sum=add1(num1, num2,num3);    printf("%d",sum);

Effect

Type 4: parameters without return values

Statement

void add(int num1,int num2);

Implementation

void add(int num1,int num2){    int sum=num1+num2;    printf("%d\n",sum);}

2. recursive functions (two simple recursive calls)

1, factorial

Function Declaration

int MyFun(int num);

Function implementation

Int MyFun (int num) {// common function // int sum1 = 1; // for (int I = 1; I <= num; I ++) {// sum1 * = I; //} // return sum1; // recursively call if (num = 1 | num = 0) {return 1 ;} else {return num * MyFun (num-1 );}}

Call

Printf ("sum = % d \ n", MyFun (6 ));

Running Effect

2. the Fibonacci series

Function Declaration

int fbsnq(int num);

Function implementation

Int fbsnq (int num) {// recursive if (num = 1 | num = 2) {return 1;} return fbsnq (num-1) + fbsnq (num-2 ); // normal // int n1 = 1, n2 = 1, temp = 0; // if (num = 1 | num = 2) {// return 1; //} // int I = 2; // for (; I <num; I ++) {// temp = n1 + n2; // n1 = n2; // n2 = temp; //} // return temp ;}

Function call

    for (int i=1; i<=30; i++) {        if ((i-1)%5==0) {            printf("\n");        }            printf("%10d",  fbsnq(i));    }    printf("\n\n");  

Running result