Arrays

Question 1

Arrays

Answer 1

Arrays are collection of similar datatype stored in a contiguous memory locations

Question 2

syntax for Arrays

Answer 2

int marks[]={1,2,3}

or

int marks[3];
scanf(“%d”,&marks[0]};
printf(“marks at 0 is %d”,marks[0]};

array mask of size three with size of 4byte each(each integer) (2 byte is for older computers),size depends on your system

say mem location be 4096,4100,4104
total memory consumed =3*4 bytes=12 bytes

Question 3

add GST of 18% to prices in list

Answer 3

include <stdio.h></stdio.h>

int main() {
float prices[3];
printf(“enter the prices\n”);
scanf(“%f”,&prices[0]);
scanf(“%f”,&prices[1]);
scanf(“%f”,&prices[2]);

printf("total price 1 is :%f",prices[0]+0.18*(prices[0]));
printf("total price 2 is :%f",prices[1]+0.18*(prices[1]));
printf("total price 3 is :%f",prices[2]+0.18*(prices[2]));

}

Question 4

Pointer arithmetic

Answer 4

some operations can be performed on pointers like increment and decrement operations

int age=22;
int *ptr=&age;
ptr++;

pointer(mem address) will increase by the size of 1 datatype ,similarly ptr–

we can also subtract one pointer from another (difference is given in no:of datatypes)

printf(“%u,%u difference =%u”,ptr,_ptr,ptr-_ptr);

we can also compare two pointer (returns 0 or 1)

printf(“comparison =%u\n”,ptr==_ptr);

Question 5

Array is a pointer itself

Answer 5

int *ptr=&arr[0];
int *ptr=arr;

both of these code are same an array is a pointer itself that points to the first memory location

Question 6

Traverse an array

Answer 6

include <stdio.h></stdio.h>

int main() {
int aadhar[5];
int *ptr=&aadhar[0];

for (int i=0;i<5;i++){
    printf("%d index : ",i);
    scanf("%d",(ptr+i));
}
for (int i=0;i<5;i++){
    printf("%d index is : %d\n",i,*(ptr+i));
}
return 0;

}

instead of (ptr+i) you can also use &aadhar[i] and aadhar[i]

Question 7

Array as function argument

Answer 7

include <stdio.h></stdio.h>

function declaration

void printnumbers(int arr[],int n);
void printnumbers(int *arr,int n);

we do not need to specify the size for which a seperate integer is used

function call

printnumbers(arr,n);

void printnumbers(int arr[],int n);
int main() {
int n,arr[]={1,2,3,4,5,6};
printnumbers(arr,6);

}
void printnumbers(int arr[],int n){
for (int i=0;i<n;i++){
printf(“%d\t”,arr[i]);
}
}

where /t stands for 1 tab

Question 8

Multi dimensional arrays

Answer 8

2D arrays

int arr[m][n]={{1,2},{3,4}};

arr[i][j]=x
arr[i][j]=y

Question 9

find the number of odds in the array

Answer 9

include <stdio.h></stdio.h>

int countodd(int arr[],int n);
int main() {
int arr[]={1,2,3,4,5,6,7};
printf(“no:of odd numbers is :%d\t”,countodd(arr,7));

}
int countodd(int arr[],int n){
int count=0;
for (int i=0;i<n;i++){
if (arr[i]%2!=0){
count++;
}
}
return count;
}

Question 10

find the out

int arr[]={1,2,3,4,5}
*(arr+2)
*(arr+5)

Answer 10

arr points to first memory address of arr

arr+2 points to the 3rd mem address
*(arr+2) =data at 3rd mem address

*(arr+5)=mem location not in array therefore 0(or value in that particular address)

Question 11

Reverse an array

Answer 11

include <stdio.h></stdio.h>

int reverse_arr(int arr[],int n);
void printnumbers(int arr[],int n);
int main() {
int arr[]={1,2,3,4,5};
reverse_arr(arr,5);
printnumbers(arr,5);

}
int reverse_arr(int arr[],int n){

for (int i=0;i<(n/2);i++){
    int first=arr[i];
    int second=arr[n-1-i];
    arr[i]=second;
    arr[n-1-i]=first;
} } void printnumbers(int arr[],int n){
for (int i=0;i<n;i++){
    printf("%d\t",arr[i]);
} }

when arrays are passed as arguments then call by reference occurs
as arr[] points to the first mem address

Question 12

store fibonacci of first n numbers in an array

Answer 12

include <stdio.h></stdio.h>

int main() {
int n;
printf(“enter n :\n”);
scanf(“%d”,&n);

int fib[n];
fib[0]=0;
fib[1]=1;

for (int i=2;i<n;i++){
    fib[i]=fib[i-1]+fib[i-2];
    printf("%d\t",fib[i]);
}
printf("\n"); }

Question 13

multiplication table using 2D array

Answer 13

include <stdio.h></stdio.h>

void storetable(int arr[][10],int m,int n,int number);

int main() {
int tables[2][10];
storetable(tables,0,10,2);
storetable(tables,1,10,3);
return 0;
}
void storetable(int arr[][10],int m,int n,int number){
for (int i=0;i<n;i++){
arr[m][n]=number*(i+1);
printf(“%d\t”,arr[m][n]);
}
printf(“\n”);
}

when you pass in 2D array (arr[][10]) as an argument then the first dimension is treated as a pointer and the second dimension is treated as a array itself therefore we should define the second dimension to avoid error

Question 14

length of an array

Answer 14

length=sizeof(array)/sizeof(datatype);

totalsize/size of one datatype