How to find the length of a string without using library function strlen

/*How to find length of a string without using library function strstr.
How to use pointer/array to find length of string sentence. C++/CPP/C program/code to find length a string/word/sentence without using inbuilt function strlen.How to find the length of a string without using library function strlen*/

#include<stdio.h>

#include<string.h>

int strLen(char *p);

int main()

{

char arr1[20];

printf("Enter a String:\n");

scanf("%s",&arr1);

printf("You entered:%s\n",arr1);

int n;

n=strLen(arr1);

printf("Strlen of entered string is:%d\n",n);

How to reverse a string using pointer or array in cpp without using strrev library function

How to reverse a string using pointer or array. CPP program for reversing a strings without using inbuilt library function strrev. How to reverse a sentence in cpp/C++/C without using library function strrev.Program to reverse a string using pointer.
#include<stdio.h>
#include<string.h>
int main()
{
char arr1[20];
printf("Enter a String:\n");
scanf("%s",&arr1);
printf("You entered:%s\n",arr1);

CPP program for concatenating two strings without using inbuilt library function strcat

How to concatenate two strings using pointer or array. CPP program for concatenating two strings without using inbuilt library function strcat. How to concatenate two strings in cpp/C++/C without using inbuilt in function strcat.Program to concatenate two strings using pointer.

#include<stdio.h>
#include<string.h>
int main()
{
char arr1[20];
printf("Enter a String:\n");
scanf("%s",&arr1);

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);

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
.
.