Q. Write an algorithm and program to concatenate two strings without using library function.

Solution : Given two Strings, the task is to concatenate the two Strings without using another string and without using concat function.

Concatenate :- Concatenation means combining two strings together.
Example :-
Input: str1 = "letsfind", str2 = "course"
Output: letsfindcourse

Algorithm For Concatenate Two Strings

//Algorithm For Concatenate Two Strings Without Using Library Function.
START
Step 1 ->  Take two string as str1 and str2.
Step 2 ->  Move to the last position of first string let it be i.
Step 3 ->  Now Loop over second string with j = 0
Assign the character str1[i] = str2[j]
Increment i and j and repeat till the last element of j.
End Loop 
Step 3 ->  Print str1.                
STOP


Program For Concatenate Two Strings

  • C
  • C++
  • Java
  • Python
  • C#
  • PHP
    • //C Program For Concatenate Two Strings Without Using Concat Function.
#include <stdio.h>
int main()
{
char str1[100] = "hello ", str2[] = "world!";
int i, j;
for (i = 0; str1[i] != '\0'; ++i);
for (j = 0; str2[j] != '\0'; ++j, ++i) {
str1[i] = str2[j];
}
str1[i] = '\0';
printf("After Concatenation Of Two String: ");
puts(str1);
return 0;
}

    //C++ Program For Concatenate Two Strings Without Using Concat Function.
#include <iostream>
using namespace std; 
int main() 
{ 
char str1[100] = "hello ", str2[] = "world!";
int i, j;
for (i = 0; str1[i] != '\0'; ++i);
for (j = 0; str2[j] != '\0'; ++j, ++i) {
str1[i] = str2[j];
}
str1[i] = '\0';
cout<<"After Concatenation Of Two String: ";
cout<<str1;
return 0; 
}

    //Java Program For Concatenate Two Strings Without Using Concat Function.
public class LFC
{
public static void main(String[] args) {
String str1 = "hello ", str2 = "world!";
int i, j;
str1=str1 + "" + str2;
System.out.println("After Concatenation Of Two String: "+str1);
}
}

    //Python Program For Concatenate Two Strings Without Using Concat Function.
str1="hello "
str2="world"
str1=str1 + "" + str2;
print("After Concatenation Of Two String: ",str1) 

    //C# Program For Concatenate Two Strings Without Using Concat Function.
using System;
class LFC {
static void Main() {
string str1="hello ",str2="world!";
str1=str1+""+str2;
Console.WriteLine("After Concatenation Of Two String: "+str1);
}
}

    //PHP Program For Concatenate Two Strings Without Using Concat Function.
<?php
$str1="hello ";
$str2="world!";
$str1=$str1.$str2;
echo "After Concatenation Of Two String: $str1";
?>
    //C Program For Concatenate Two Strings Without Using Concat Function.
#include <stdio.h>
int main()
{
char str1[100] = "hello ", str2[] = "world!";
int i, j;
for (i = 0; str1[i] != '\0'; ++i);
for (j = 0; str2[j] != '\0'; ++j, ++i) {
str1[i] = str2[j];
}
str1[i] = '\0';
printf("After Concatenation Of Two String: ");
puts(str1);
return 0;
}

    Output

    After Concatenation Of Two String: hello world!

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