Programming Example

Concatenate Two Strings Without Using strcat()

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💻 Practical Program

📘 Step by Step Learning

To understand this example, you should have the knowledge of the following C programming topics:

C Arrays
C Programming Strings
C for Loop

As you know, the best way to concatenate two strings in C programming is by using the strcat() function. However, in this example, we will concatenate two strings manually.

Program Code

#include <stdio.h>
int main() {
  char s1[100] = "programming ", s2[] = "is awesome";
  int length, j;

  // store length of s1 in the length variable
  length = 0;
  while (s1[length] != '\0') {
    ++length;
  }

  // concatenate s2 to s1
  for (j = 0; s2[j] != '\0'; ++j, ++length) {
    s1[length] = s2[j];
  }

  // terminating the s1 string
  s1[length] = '\0';

  printf("After concatenation: ");
  puts(s1);

  return 0;
}

Output

After concatenation: programming is awesome

Explanation

Here, two strings s1 and s2 and concatenated and the result is stored in s1.

It's important to note that the length of s1 should be sufficient to hold the string after concatenation. If not, you may get unexpected output.

How to learn from this program

First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.

Practice suggestion

After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.