strcat() Function in C: Concatenating Strings

strcat( ) function in C language concatenates two given strings. It concatenates source string at the end of destination string. Syntax for strcat( ) function is given below.

Syntax

char * strcat ( char * destination, const char * source );

Parameters

strng1- this is a string(Like: "hi") strng2- this is a string(Like: "hello")

Returns

This function concatenates the source string at the end of the target string. For example, "Hi" and "Hello" on concatenation would result into a string "HiHello".

Program 1

<span class="pln">
</span><span class="com">#include</span><span class="str">&lt;stdio.h&gt;</span><span class="pln">
</span><span class="com">#include</span><span class="str">&lt;string.h&gt;</span><span class="pln">

</span><span class="kwd">int</span><span class="pln"> main</span><span class="pun">(</span><span class="pln"> </span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
   </span><span class="kwd">char</span><span class="pln"> strng1</span><span class="pun">[</span><span class="pln"> </span><span class="pun">]</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Hello "</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
   </span><span class="kwd">char</span><span class="pln"> strng2</span><span class="pun">[</span><span class="pln"> </span><span class="pun">]=</span><span class="pln"> </span><span class="str">"Hi"</span><span class="pln"> </span><span class="pun">;</span><span class="pln">

   printf </span><span class="pun">(</span><span class="pln"> </span><span class="str">"\nSource string = %s"</span><span class="pun">,</span><span class="pln"> strng1 </span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
   printf </span><span class="pun">(</span><span class="pln"> </span><span class="str">"\nTarget string = %s"</span><span class="pun">,</span><span class="pln"> strng2 </span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">

   strcat</span><span class="pun">(</span><span class="pln">strng1</span><span class="pun">,</span><span class="pln"> strng2</span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">

   printf</span><span class="pun">(</span><span class="str">"\nTarget string after strcat() = %s \n"</span><span class="pun">,</span><span class="pln"> strng1</span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span>

Output

Source string = Hello
Target string = Hi
Target string after strcat() = Hello Hi
Press any key to continue . . .

Program 2

<span class="pln">
</span><span class="com">#include</span><span class="str">&lt;stdio.h&gt;</span><span class="pln">
</span><span class="com">#include</span><span class="str">&lt;string.h&gt;</span><span class="pln">
</span><span class="kwd">void</span><span class="pln"> main</span><span class="pun">(</span><span class="pln"> </span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
</span><span class="kwd">char</span><span class="pln"> source</span><span class="pun">[</span><span class="pln"> </span><span class="pun">]</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="str">"Don!"</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
</span><span class="kwd">char</span><span class="pln"> target</span><span class="pun">[</span><span class="lit">30</span><span class="pun">]</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> </span><span class="str">"I am "</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
strcat </span><span class="pun">(</span><span class="pln"> target</span><span class="pun">,</span><span class="pln"> source </span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
printf </span><span class="pun">(</span><span class="pln"> </span><span class="str">"\nsource string = %s"</span><span class="pun">,</span><span class="pln"> source </span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
printf </span><span class="pun">(</span><span class="pln"> </span><span class="str">"\ntarget string = %s \n"</span><span class="pun">,</span><span class="pln"> target </span><span class="pun">)</span><span class="pln"> </span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span>

Output

source string = Don!
target string = I am Don!
Press any key to continue . . .

Note that the target string has been made big enough to hold the final string.