Pointer to array of character,array of integer&array of array in c

Pointer to array of character in c

Pointer to array of character: A pointer to such an array which contents is character constants is known as pointer to array of character constant.

What will be output if you will execute following code?


#include<stdio.h>

char display(char (*)[]);

int main(){

char c;

char character[]={65,66,67,68};

char (*ptr)[]=&character;

c=display(ptr);

printf("%c",c);


return 0;

}

char display(char (*s)[]){

**s+=2;

return **s;

}

Output: C

Explanation: Here function display is passing pointer to array of characters and returning char data type.

**s+=2

=>**s=**s+2

=>**ptr=**ptr+2 //s=ptr

=>**&character= **&character+2 //ptr=&character

=>*character=*character+2 //from rule *&p =p

=>character[0]=character[0]+2 //from rule *(p+i)=p[i]

=>character [0] =67

**s=character [0] =67

Note: ASCII value of ‘C’ is 67

Pointer to array of integer in c

Pointer to array of integers: A pointer to such an array which contents are integer numbers is known as pointer to array of integer.

What will be output if you will execute following code?


#include<stdio.h>

int main(){

static int i,j,k;

int *(*ptr)[];

int *array[3]={&i,&j,&k};

ptr=&array;

j=i+++k+10;

++(**ptr);

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


return 0;

}

Output: 10

Explanation:

In this example:

array []: It is array of size three and its content are address of integer.

ptr: It is pointer to array which content are address of integer.

Pictorial representation above declaration:

Note: In the above figure upper part of box represent content and lower part represent memory address. We have assumed arbitrary address.

j=i+++k+10

=i++ + k+10

=0 +0 +10=10

***ptr = *** (&array) //ptr=&array

= **array //From rule *&p=p

//From rule array [0] =*(array+0) and ++ (**ptr)

=*array [1]

=*&j

=j

=10

What will be output if you will execute following code?


#include<stdio.h>

int main(){

int i,j,k;

int *(*ptr)[];

int *array[3]={&i,&j,&k};

ptr=&array;

j=i+++k+10;

++(**ptr);

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


return 0;

}

Output: Compiler error

Explanation: Address of auto variable cannot be member of an array.

Pointer to array of array in c

Examples of pointer to array of array in c:


What will be output if you will execute following code?


#include<stdio.h>

int main(){

static float farray[][3]={0.0f,1.0f,2.0f,3.0f,4.0f,5.0f,6.0f,7.0f,8.0f};

float (*array[3])[3]={&farray[0],&farray[1],&farray[2]};

float (*(*ptr)[])[3]=&array;

printf("%f ",2[(*(**ptr+1))]);


return 0;

}

Output: 5.000000

Explanation:

In this example:

farray [][3]: It is two dimension array and its content are float constants.

array [3]:It is one dimension array and its content are address of such one dimension array which content are float constant.

ptr: It is pointer to one dimension array which content are address of such one dimension array which content are float constant.

Pictorial representation:

Note: In the above figure upper part of box represent content and lower part represent memory address. We have assumed arbitrary address.

2[(*(**ptr+1))]

= (*(**ptr+1)) [2]

= (*(**&array+1)) [2]

= (*(*array+1)) [2]

= (*(array [0] +1)) [2]

= (*(&farray [0] +1)) [2]

=&farray [0] [1] [2]

=*&farray [1] [2]

=farray [1] [2]

It is 1*(3) +2=5^th element of farray starting from zero which is 5.0f

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