How to put the string entered into a character array in C++?

Question

Now, I am facing with such a problem: Compare two strings without using "strcmp" in library function.

I have defined the function "mystrcmp" correctly, but I also have to put the string entered into a character array. How can I realize it?

Here is my wrong codes:

char a1[100],a2[100];
int j=0;
do
{
    cin>>a1[j];
    j=j+1;
}while(getchar()!=10);
int k=0;
do
{
    cin>>a2[k];
    k=k+1;
}while(getchar()!=10);

cout<<j<<"  "<<k<<"\n"; 

I want to see if the loops are correct through j and k. Unfortunately, the results are wrong. For example, when I enter "abcdefg" and "gfedcba", I get the result "j=4, k=4".

What's wrong with my codes? How can I correct it?

I'm looking forward to your answers. Thank you.

Answer 1

Why are you using the value 10 in your code? Don't use integer literals in place of character constants, because when you attempt to run this code on a computer that uses the EBCDIC character set you'll notice that '\n' has the value 37, not 10. Use '\n' instead of 10.

Don't mix getchar and cin code. That's a pretty bad idea, because they both consume one character each. In other words, getchar() is consuming one byte, and cin is consuming one byte, so you're consuming two bytes per loop and only storing one of those bytes. If you're going to use getchar, I think you mean something like this:

for (int c = getchar(); c >= 0 && c != '\n'; c = getchar()) {
    a1[j++] = c;
}
a1[j] = '\0';

The same sort of thing using C++'s cin:

for (int c = cin.get(); cin.good() && c != '\n'; c = cin.get()) {
    a1[j++] = c;
}
a1[j] = '\0';