ARRAYS TUTORIAL

Array in c

Array tutorials in c programming language by examples

An array is derived data type in c programming language which can store similar type of data in continuous memory location. Data may be primitive type (int, char, float, double…), address of union, structure, pointer, function or another array.

Example of array declaration:

int arr[5];

char arr[5];

float arr[5];

long double arr[5];

char * arr[5];

int (arr[])();

double ** arr[5];

Array is useful when:

(a) We have to store large number of data of similar type. If we have large number of similar kind of variable then it is very difficult to remember name of all variables and write the program. For example:

//PROCESS ONE
#include<stdio.h>

int main(){

    int ax=1;

    int b=2;

    int cg=5;

    int dff=7;

    int am=8;

    int raja=0;

    int rani=11;

    int xxx=5;

    int yyy=90;

    int p;

    int q;

    int r;

    int avg;

    avg=(ax+b+cg+dff+am+raja+rani+xxx+yyy+p+q+r)/12;

    printf("%d",avg);

    return 0;        

}

If we will use array then above program can be written as:

//PROCESS TWO
#include<stdio.h>

int main(){

    int arr[]={1,2,5,7,8,0,11,5,50};

    int i,avg;

    for(int i=0;i<12;i++){

         avg=avg+arr[i];

    }

    printf("%d",avg/12);
    return 0;         

}

Question: Write a C program to find out average of 200 integer number using process one and two.

(b) We want to store large number of data in continuous memory location. Array always stores data in continuous memory location.

(q) What will be output when you will execute the following program?

#include<stdio.h>

int main(){

int arr[]={0,10,20,30,40};

    char *ptr=arr;

    arr=arr+2;

    printf("%d",*arr);
    return 0;         

}

Advantage of using array:

1. An array provides singe name .So it easy to remember the name of all element of an array.

2. Array name gives base address of an array .So with the help increment operator we can visit one by one all the element of an array.

3. Array has many application data structure.

Array of pointers in c:

        Array whose content is address of another variable is known as array pointers.  For example:

#include<stdio.h>

int main(){

float a=0.0f,b=1.0f,c=2.0f;

    float * arr[]={&a,&b,&c};

    b=a+c;

    printf("%f",arr[1]);
    return 0;         

}

Complex arrays in c

1. Declaration of an array of size five which can store address such functions whose parameter is void data type and return type is also void data type:

void ( arr[5] )( );

2. Declaration of an array of size five which can store address such function which has two parameter of int data type and return type is  float data type:

float ( arr[5] )(int, int);

3. Declaration of an array of size two which can store the address of printf or sacanf function:

int ( arr[2] )( const char *, … );

Note: prototype of printf function is:  int printf( const char *, … );

Different type of array in c:

(a) Array of integer

    An array which can hold integer data type is known as array of integer.

(b) Array of character

    An array which can hold character data type is known as array of character.

(c) Array of union

    An array which can hold address of union data type is known as union of integer.

For example:

(1) What will be output when you will execute the following program?

#include<stdio.h>

union A{

char p;

float const * const q;

};

int main(){

    union A arr[10];

    printf("%d",sizeof arr);
   return 0;      
}

  

Output: 20

(2) What will be output when you will execute the following program?

#include<stdio.h>
union A{

    char character;

    int ascii;

};

int main(){

    union A arr[2]={{65},{'a'}};

    printf("%c %c",arr[0],arr[1]);
       return 0;      

}

  

Output: A a

(d) Array of structure

 An array which can hold address of structure data type is known as array of structure. For example:

(1) What will be output when you will execute the following program?


#include<stdio.h>

typedef struct stu{

    char * name;

    int roll;

}s;

int main(){

    s arr[2]={{"raja",10},{"rani",11}};

    printf("%s %d",arr[0]);

    return 0;         
}

Output: raja 10

(2) What will be output when you will execute the following program?


#include<stdio.h>

struct A{

    int p;

    float q;

    long double *r;

};

int main(){

    struct A arr[10];

    printf("%d",sizeof arr);

   
    return 0;         
}

Output: 80

(e) Array of string

    An array which can hold integer data type is known as array of integer.

(f) Array of array

    An array which can hold address of another array is known as array of array.

(g) Array of address of integer

    An array which can hold address integer data type is known as array of address of integer.

Pointer to array

A pointer which holds base address of an array or address of any element of an array is known as pointer to array. For example:

(a)

#include<stdio.h>

int main(){

    int arr[5]={100,200,300};

    int *ptr1=arr;

    char *ptr2=(char *)arr;

    printf("%d   %d",*(ptr1+2),*(ptr2+4));

       return 0;       

}

Output: 300   44

(b)

#include<stdio.h>

int main(){

    static int a=11,b=22,c=33;

    int * arr[5]={&a,&b,&c};

    int const * const *ptr=&arr[1];

    --ptr;

    printf("%d ",**ptr);
        return 0;        

}