I'm learning string in c, and i'm working on my homework which ask me to write a program to replace part of string under certain circumstances. Here is my source code(undone):

#include <stdio.h>
#include <string.h>
int main()
{
    char str1[128], str2[128], str3[128];
    for (int i = 0; i < 128; i++) //initialize str
    {
        str1[i] = 0;
        str2[i] = 0;
        str3[i] = 0;
    }
    printf("Input the first string:"); //inputs
    fgets(str1, 128, stdin);
    printf("Input the second string:");
    fgets(str2, 128, stdin);
    printf("Input the third string:");
    fgets(str3, 128, stdin);
    if (strncmp(str1, str2, strlen(str2) - 1) == 0) //if the first n charters match (n=length of str2)
    {
        printf("%s", str3); //print str3
        int RemainingChar = 0;
        RemainingChar = strlen(str1) - strlen(str2);
        for (int i = 0; i < RemainingChar; i++)
        {
            printf("%c", str1[i + strlen(str2) - 1]); //print the remaining part
        }
    }
    return 0;
}

Here is how it run:

Input the first string:asdfghjkl
Input the second string:asd
Input the third string:qwe
qwe
fghjkl

There is an unexpected line break. what should I do to make it output like this:qwefghjkl?