20130426

How to search a substring in C++/Cpp without using library function strstr


/*How to search a sub string without using library function strstr. 
How to use pointer/array to search substring in a string sentence.
C++/CPP/C program/code to search a word in a sentence without using inbuilt function strstr*/
#include<stdio.h>
#include<string.h>
int main()
{
char arr1[50];
printf("Enter a String:\n");
scanf("%s",&arr1);

char arr2[20];
printf("Enter a String:\n");
scanf("%s",&arr2);
printf("Searching for:%s\n",arr2);

20130425

How to use make file in CPP C+++ C

/*What is makefile  ?
---------------------------------------
makefile is a script/utility  that contains target, dependencies and actions to compile modified file/files in a project of multple files.  */

/*SYNTAX
-----------------------------------
target:dependencies
[tab]  actions
.
.

20130422

How to implement msgq message queue in CPP C C++


//Program to implement msgq
/*CPP Program for msg queue in Linux
pipes work with related process parent-child only.
Fifo can make unrelated process to communicate but
fifo created does not persists for use in future.
Shared memory is similar to fifo but over comes this and can be used later also.
Program to implement IPC Message Queues IPC mechanism.
msgqSendkirk.c adds the message on the message queue.
msgqRecvSpock.c reads and removes the message from the message
queue.To use this program first compile and run msgqSendkirk.c
to add a message to the message queue. To see the
Message Queue in other terminal run msgqRecvSpock.c
ipcs -q shows the msg ques.
ipcrm -q 131073 removes the msgq created say 131071 */
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
//1. declaring the msg structure
struct my_msgbuf
{

20130421

How to use callback function pointer in cpp/C/C++

Program for callback /function pointer in CPP/C/C++

What is function pointers?As we know a pointer is a special variable that folds the address of another variable.
Function pointer is also  a pointer that hold the address of a function.
Int array[10]; // here array is a constant pointer to a 10 element array. That is constant pointer to first element of array.
Can we declare a non-constant pointer to a function? Yes we can .
Int (*funcPtr)();//funcPtr is a pointer to a function that takes no arguments and returns an integers.//parenthesis is must here as we are not assigning the return type.
Int (*funcPtr)(int,int);//funcPtr is a pointer to a function that takes two arguments and returns an integers.

20130413

How to use malloc for 2d array dynamic memory allocation


/*How to use malloc for 2d array dynamic memory allocation. How to write 2-d array with dynamic memory allocation */
#include<stdio.h>
#include<malloc.h>
int main()
{
int r,c,i,j;
printf("Enter No of rows and columns:");
scanf("%d%d",&r,&c);

int **array;
array=(int**)malloc(r*sizeof(int));

for(i=0;i<r;i++)
{
array[i]=malloc(c*sizeof(int));
}