string_joiner.c

// ask for two strings and join the first half of the first string
// with the second half of the second string.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>

#define SIZE 255 

bool getInput( char *aString ) {
  printf( "Please enter a long string: " );
  if( fgets( aString, SIZE, stdin ) == aString ) {
    int lastElement = strlen( aString ) - 1;
    if( aString[ lastElement ] == '\n' || aString[ lastElement ] == '\r' ) {
      aString[ lastElement ] = '\0';
    }
    return true;
  }
  return false;
}

void printStringSize( char *aString ) {
  printf( "The string \"%s\" is %zu bytes long\n", aString, strlen( aString ) );
}

int main( void ) {
  char
    firstString[ SIZE ],
    secondString[ SIZE ],
    thirdString[ SIZE ];

  if( getInput( firstString ) ) {
    if( getInput( secondString ) ) {
      printStringSize( firstString );
      printStringSize( secondString );

      int firstStringHalfwidth = strlen( firstString ) / 2;
      int secondStringHalfwidth = strlen( secondString ) / 2;
      int lastHalfOfSecondString = strlen( secondString ) - secondStringHalfwidth;

      strncpy( thirdString, firstString, firstStringHalfwidth );
      strncpy(
        &thirdString[ firstStringHalfwidth ],
        &secondString[ secondStringHalfwidth ],
        lastHalfOfSecondString );

      printf( "%s\n", thirdString );
      return 0;
    }
  }
  err( 1, "For some reason I was unable to get input from you. Oh well.\n" );
  return 1;
}