How to combine 2 arrays without using strncat? - arrays

Question

I currently try to combine 2 arrays without using strncat. The following code doesnt work and the problem lies in one of the for loops. I guess that some of these boundaries are wrong, but I'm not capable of finding the mistake:
#include <stdio.h>
int main() {
char text1[] = {"Hello"};
char text2[] = {", how are you?"};
char result[100];
int count1 = strlen(text1);
int count2 = strlen(text2);
printf("%d\n", count1);
printf("%d\n", count2);
for(int i = 0; i<count1; i++) {
result[i] = text1[i];
}
for(int k = 0; k<count2; k++) {
result[k+1+count1] = text2[k];
}
for(int j = 0; j<count1+count2; j++) {
printf(" %s", result[j]);
}
return 0;
}

Answer 1

#include <stdio.h>
#include <string.h>
int main() {
char text1[] = "Hello"; //correct way to initialize string
char text2[] = ", how are you?";
char result[100];
int count1 = strlen(text1);
int count2 = strlen(text2);
printf("%d\n", count1);
printf("%d\n", count2);
for(int i = 0; i<count1; i++) {
result[i] = text1[i];
}
for(int k = 0; k<count2; k++) {
result[k+count1] = text2[k]; //k + 1 + count1 causes bug
}
result[count1+count2] = '\0' ; //adding NULL char at the end
printf("%s\n" , result) ; //printing the string using %s
return 0;
}

Answer 2

Instead of defining the size of your result array as 100, you should define it equal to the sum of the length of both the input arrays.
Also, the format specifier should be %c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main() {
char text1[] = {"Hello"};
char text2[] = {", how are you?"};
int count1 = strlen(text1);
int count2 = strlen(text2);
char *result = malloc(count1 + count2);
printf("%d\n", count1);
printf("%d\n", count2);
for(int i = 0; i<count1; i++) {
result[i] = text1[i];
}
for (int i = 0; i < count2; i++) {
result[count1 + i] = text2[i];
}
for (int i = 0; i < count1 + count2; i++) {
printf("%c", result[i]);
}
return 0;
}

Answer 3

You do it with fewer variables and a lot less code. You've lost track of what is what and 'skip' a space with 'k+1+count1'... Then try to print, in a loop, characters using a %s format specifier. Too complicated!
#include <stdio.h>
int main() {
char result[100], text1[] = "Hello", text2[] = ", how are you?";
int i = 0, j = 0;
while( (result[ i ] = text1[ i ] ) != '\0' )
i++;
while( (result[ i ] = text2[j++] ) != '\0' )
i++;
puts( result );
return 0;
}
The output is as expected.

Answer 4

So this is the code that works and i've explained each line after the code snippet.
#include <stdio.h>
#include<string.h>
int main() {
char text1[] = "Hello";
char text2[] = ", how are you?";
char result[100];
int count1 = strlen(text1);
int count2 = strlen(text2);
printf("%d\n", count1);
printf("%d\n", count2);
for(int i=0 ; i<(count1+count2); i++){
if(i<count1)
{
result[i]= text1[i];
}
else{
result[i]=text2[i-count1];
}
}
for(int j = 0; j<count1+count2; j++) {
printf("%c", result[j]);
}
return 0;
}
In the first loop, you'd see i'm iterating from 0 to the sum of both the string sizes as i'm assuming that there's a single large string instead of two seperate ones.
As you mentioned that count1 is the size of text1 and count2 as the size of text2, so the logic i used here is that as long as the value of i is lesser than the size of the text1, I'm taking the characters from that position in the text and assigning it to the result string, then once i exceeds that, i'm subtracting the count1 value from the i value as it will again take characters from the 0th position from the text2 and assigning it to the result string.
I would also like to also mention that when you initialise a character array as a string, you just use " ", not {" "} and also when you're printing a character array so you use "%c" not "%s" unless you're printing out a string which you do use "%s" and if so, you can remove the looping statement.
Hope this helps!