Programming Tutorials

strcat() and strncat() sample program in C++

By: Reema sen  

Related to strcpy() and strncpy() are the standard functions strcat() and strncat(). The former concatenates one string to another; that is, it appends the string it takes as its second parameter to the end of the string it takes as its first parameter. strncat(), as you might expect, appends the first n characters of one string to the other. The sample program illustrates their use.

Using strcat() and strncat().

1:     #include <iostream.h>
2:     #include <string.h>
3:
4:
5:     int main()
6:     {
7:        char stringOne[255];
8:        char stringTwo[255];
9:
10:       stringOne[0]='\0';
11:       stringTwo[0]='\0';
12:
13:       cout << "Enter a  string: ";
14:       cin.getline(stringOne,80);
15:
16:       cout << "Enter a second string: ";
17:       cin.getline(stringTwo,80);
18:
19:       cout << "String One: " << stringOne << endl;
20:       cout << "String Two: " << stringTwo << endl;
21:
22:       strcat(stringOne," ");
23:       strncat(stringOne,stringTwo,10);
24:
25:       cout << "String One: " << stringOne << endl;
26:       cout << "String Two: " << stringTwo << endl;
27:
28:     return 0;
29: }

Output: Enter a string: Oh beautiful
Enter a second string: for spacious skies for amber waves of grain
String One: Oh beautiful
String Two: for spacious skies for amber waves of grain
String One: Oh beautiful for spacio
String Two: for spacious skies for amber waves of grain

Analysis: On lines 7 and 8, two character arrays are created, and the user is prompted for two strings, which are put into the two arrays.

A space is appended to stringOne on line 22, and on line 23, the first ten characters of stringTwo are appended to stringOne. The result is printed on lines 25 and 26.