Multithreading C++ code

Multithreading in C++ - 

 

In Operating system, Multithreading provides the capability to process multiple threads at the same time by a CPU rather than processing multiple processes. 

Examples of Multithreading - 

• Spelling checker and Grammar checker in Microsoft word at the same time

Below is c++ implementation of multithreading.

Here we are multiplying two matrices using multithreading - 

C++ code for Multithreading -

#include<stdio.h>

#include<unistd.h>

#include<stdlib.h>

#include<semaphore.h>

#include<sys/types.h>

#include<pthread.h>

#define pf printf

#define sf scanf

int m1[100][100],m2[100][100],i,j,k,res[100][100],r,c,sum;

void *input(void *arg)

{

pf("enter the size of matrix m1(row*col):\n");

sf("%d%d",&r,&c);

printf("enter the matrix elements:\n");

for(i=0;i<r;i++)

for(j=0;j<c;j++)

sf("%d",&m1[i][j]);

pf("enter the size of matrix m2(row*col):\n");

sf("%d%d",&r,&c);

printf("enter the matrix elements:\n");

for(i=0;i<r;i++)

for(j=0;j<c;j++)

sf("%d",&m2[i][j]);

}

void *multiplication(void *arg)

{

for(i=0;i<r;i++)

{

for(j=0;j<c;j++)

{

sum=0;

for(k=0;k<r;k++)

sum+=m1[i][k]*m2[k][j];

res[i][j]=sum;

}

}

}

void *print(void *arg)

{

pf("Resultant Matrix:\n");

for(i=0;i<r;i++)

{

for(j=0;j<c;j++)

pf("%d ",res[i][j]);

pf("\n");

}

}

int main()

{

pthread_t p[3];

pthread_create(&p[0],NULL,input,NULL);

sleep(15);

pthread_create(&p[1],NULL,multiplication,NULL);

pthread_create(&p[2],NULL,print,NULL);

pthread_join(p[0],NULL);

pthread_join(p[1],NULL);

pthread_join(p[2],NULL);

return 0;

}