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// void pointer- A void pointer is a special pointer type that can hold the // address of any data type. //dereferencing of void pointer can only be done after typecasting into other data type. #include<stdio.h> void main() { void *vp; int a=10; float b=5.5; char ch='b'; vp=&a; printf("%d\n",*(int*)vp); vp=&b; printf("%f\n",*(float*)vp); vp=&ch; printf("%c",*(char*)vp); }

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#include<stdio.h> void main() { int a[]={10,11,-1,56,67,5,4}; int *p,*q; p=&a[0]; q=&a[0]+3; printf("%d,%d,%d\n",(*p)++,(*p)++,*(++p)); printf("%d\n",*p); printf("%d\n",(*p)++); printf("%d\n",(*p)++); q--; printf("%d\n",(*(q+2))--); printf("%d\n",*(p+2)-2); printf("%d\n",*(p++-2)-1); }

#include<stdio.h> void main() { int a[7]={4,8,3,6,1,2,7}; int *p=&a[0],*q; printf("%d\n",*p); //4 printf("%d,%d,%d\n",(*p)++,*p++,*++p); //3,8,8 printf("%d\n",*p); //4 q=p+3; //q is pointing to a[5] printf("%d\n",*q-3); //-1 printf("%d\n",*--p+5); //13 printf("%d\n",*p+*q); //10 }

//Performing increment and decrement on pointer #include<stdio.h> void main() { int a[5]={5,4,6,8,3}; int *p=&a[0]; printf("Value:%d\n",*p); // Value:5 p++; // now,p is pointing to a[1] printf("Value:%d\n",*p); // Value:4 ++p; // now p is pointing to a[2] printf("Value:%d\n",*p); // value:6 p--; // now p is pointing to a[1] printf("Value:%d\n",*p); // value:4 --p; // now p is pointing to a[0] printf("Value:%d\n",*p); // Value:5 }

// performing subraction on pointers. #include<stdio.h> void main() { int a[5]={6,4,2,5,8}; int *p=&a[0]; int *q=&a[4]; printf("p-q=%d\n",p-q); //p-q=-4 *q=15; // now a[4]=15 printf("q-p=%d\n",q-p); //q-p=4 *p=32; //now ,a[0]=32 q=q-3; //now q is pointing to a[1] printf("value:%d\n",*q); //value:4 p=p+3; //now p is pointing to a[3] printf("value:%d\n",*p); //value:5 printf("p-q=%d\n",p-q); //p-q=2 }

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//performing addition on pointer. #include<stdio.h> void main() { int a[5]={5,3,9,7,2}; int *p=&a[0]; printf("Value : %d\n",*p); //Value :5 printf("Address of element:%u\n",p); //Adress of element:6422280 p=p+2; //The pointer will point to a[2] *p=4; //Now the value of a[2] is modified to 4 printf("Value :%d\n",*p); //Value:9 printf("Address of element:%u\n",p); //Adress of element:6422288 }

// // pointer is a variable which stores the adress of other variable. // // int *p :- p is a pointer variable which stores the adress of any other int type variable // // (&)adress of (*) indirection/dereferencing operator // #include<stdio.h> // void main() // {int a=5,b=6; // int *p,*q; //declaration of pointers p and q // p=&a; // pointer variable p,has the address of variable a // q=&b; // pointer variable q, has the adress of variable b // printf("Value of a:%d\n",*p); //*p will give the value of a i.e *(&a) value at adress of a // printf("Value of b:%d",*q); //*q will give the alue of b i.e *(&b) value at adress of b // } //performing addition on pointer. #include<stdio.h> void main() { int a[5]={5,3,9,7,2}; int *p=&a[0]; printf("Value : %d\n",*p); //Value :5 printf("Address of element:%u\n",p); //Adress of element:6422280 p=p+2; //The pointer will point to a[2] *p=4; //Now the value of a[2] is modified to 4 printf("Value :%d\n",*p); //Value:9 printf("Address of element:%u\n",p); //Adress of element:6422288 }

// pointer is a variable which stores the adress of other variable. // int *p :- p is a pointer variable which stores the adress of any other int type variable // (&)adress of (*) indirection/dereferencing operator #include<stdio.h> void main() {int a=5,b=6; int *p,*q; //declaration of pointers p and q p=&a; // pointer variable p,has the address of variable a q=&b; // pointer variable q, has the adress of variable b printf("Value of a:%d\n",*p); //*p will give the value of a i.e *(&a) value at adress of a printf("Value of b:%d",*q); //*q will give the alue of b i.e *(&b) value at adress of b }

// Program to reverse a sring using a loop. #include<stdio.h> #include<string.h> int main() { char str[50]; printf("Enter the string:"); gets(str); int i,l=strlen(str); for(i=0;i<l/2;i++) { char ch=str[i]; str[i]=str[l-1-i]; str[l-1-i]=ch; } printf("Reversed string:\n%s",str); return 0; }

// Program to reverse a sring using strrev function. #include<stdio.h> #include<string.h> int main() { char str[20]="coding"; strrev(str); printf("Reversed string:\n%s",str); return 0; }

// Program to concatenate two strings using a loop. #include<stdio.h> #include<string.h> int main() { int l1,l2,i; char s1[50]="C_"; char s2[50]="Programming"; l1=strlen(s1); l2=strlen(s2); for(i=0;i<=l2;i++) { s1[l1+i]=s2[i]; } printf("Concatenated string:\n%s",s1); return 0; }

// Program to concatenate two strings using strcat function. #include<stdio.h> #include<string.h> int main() { char s1[50]="C_"; char s2[50]="Programming"; strcat(s1,s2); printf("Concateated string:\n%s",s1); return 0; }

// Program to find length of a string using a loop. #include<stdio.h> int main() { int len=0,i; char string[100]; printf("Enter string:"); gets(string); for(i=0;string[i]!='\0';i++) { len++; } printf("Length of the string is: %d",len); return 0; }

// Program to find length of a string using strlen function #include<stdio.h> #include<string.h> int main() { int len=0; char string[100]; printf("Enter string:"); gets(string); len=strlen(string); printf("Length of the string is: %d",len); return 0; }

//Program to read a string and print it. #include<stdio.h> int main() {char name[20]; printf("Enter name:"); gets(name); puts(name); return 0; }

//Program for matrix multiplication. #include<stdio.h> int main() {int r1,c1,r2,c2; printf("Enter number of rows in first matrix:"); scanf("%d",&r1); printf("Enter number of coulumns in first matrix:"); scanf("%d",&c1); printf("Enter number of rows in second matrix:"); scanf("%d",&r2); printf("Enter number of coulumns in second matrix:"); scanf("%d",&c2); if(c1==r2) //two matrices can be multiplied only if coloumns of first matrix is equal to rows of second matrix { printf("The matrices can be multiplied.\n"); int a[r1][c1],b[r2][c2],c[r1][c2],i,j,k,sum=0; printf("Enter the elements of first matrix:\n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { printf("Enter the Element at a[%d][%d]:",i,j); scanf("%d",&a[i][j]); } } printf("Enter the Elements of second matrix:\n"); for(i=0;i<r2;i++) { for(j=0;j<c2;j++) { printf("Enter the Element at b[%d][%d]:",i,j); scanf("%d",&b[i][j]); } } for(i=0;i<r1;i++) { for(j=0;j<c2;j++) { sum=0; for(k=0;k<c1;k++) { sum=sum+(a[i][k]*b[k][j]); } c[i][j]=sum; } } printf("Matrix 1:\n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { printf("%d\t",a[i][j]); } printf("\n"); } printf("Matrix 2:\n"); for(i=0;i<r2;i++) { for(j=0;j<c2;j++) { printf("%d\t",b[i][j]); } printf("\n"); } printf("Matrix 1 * Matrix 2:\n"); for(i=0;i<r1;i++) { for(j=0;j<c2;j++) { printf("%d\t",c[i][j]); } printf("\n"); } } else{ printf("Matrix cannot be multipled Enter the row and column number correctly."); } return 0; }

//Program to do sum of 2 matrices and store the sum in third matrix, read the elements of matrix. #include<stdio.h> int main() {int a[2][3],b[2][3],c[2][3],i,j; printf("Enter elemnts of first matrix:\n"); for(i=0;i<2;i++) { for(j=0;j<3;j++) { printf("Enter the element at a[%d][%d]:",i,j); scanf("%d",&a[i][j]); } } printf("Enter elemnts of second matrix:\n"); for(i=0;i<2;i++) { for(j=0;j<3;j++) { printf("Enter the element at b[%d][%d]:",i,j); scanf("%d",&b[i][j]); } } for(i=0;i<2;i++) { for(j=0;j<3;j++) { c[i][j]=a[i][j]+b[i][j]; } } printf("The sum of two matices=\n"); for(i=0;i<2;i++) { for(j=0;j<3;j++) { printf("%d\t",c[i][j]); } printf("\n"); } return 0; }