Why is this '\n' causing a run time error?

[MarkyMark]

#include <iostream>
#include <cstring>

void replace_substring(char *, char *, char *);

int main()
{

	const int SIZE = 50;
	char str1[SIZE] = "the dog jumped over the fence";
	char str2[SIZE] = "the\n";//Here is the '\n' that is causing problems
	char str3[SIZE] = "that";

	replace_substring(str1, str2, str3);
	return 0;
}

void replace_substring(char * string1, char *string2, char *string3)
{
	char *strPtr = nullptr;

	strPtr = strstr(string1, string2);
	
	std::cout << strPtr;
}

Here is the program, the '\n' char is what is causing the program to crash, when I remove it the program prints fine. Obviously I know what the problem is but I'm not sure why it does this? What is going on behind the computer that the newline char is causing the program to crash?

[Zhuge]

I'd guess it is crashing because it is looking for "the\n" inside of "the dog jumped over the fence"; this fails, so strstr() returns nullptr. Then you try to print that string to standard output on 24, which crashes as it tries to dereference that null pointer.

[MiiNiPaa]

As Zhuge said. See for yourself:

void replace_substring(char * string1, char *string2, char *string3)
{
    char *strPtr = nullptr;

    strPtr = strstr(string1, string2);
    if (!strPtr) std::cerr << "Null Pointer detected!";
    //std::cout << strPtr;
}