Wrong Output : counting the string - c++

Question

#include <iostream>
#include <cstring>
using namespace std;
int main() {
char a[10001],b[10001];
int tot,s1,s2;
cin>>tot;
while(tot!=0) {
gets(a);
gets(b);
s1= strlen(a);
s2= strlen(b);
cout<<s1<<s2<<endl;
tot--;
s1=0;
s2=0;
}
}
this is a program to find length of two strings , with cases also entered
Input :
4
abcd
xyz
abcd
bcda
aabc
acaa
Codechef
elfedcc
Expected output
43
44
44
87
but output is
04
34
44
48
Why?

Answer 1

As noted in the comment, the compiler is punishing you for using gets1. I wasn't going to write an actual answer, but the answers you're getting seem to be trying to cover up the problems with the code, without actually fixing anything.
First: never use gets. There's simply no way to use it safely, and no excuse for even trying. It's just a badly designed function and we'd all be better off if it had never existed.
Second, in C++ there's almost never a good reason to use arrays of char for strings. strlen is pretty much the same way. These aren't as dangerous or horrible as gets but real reasons to use them in C++ (outside of things like extremely limited embedded systems) is sufficiently rare that until you know what you're doing and why, it's probably best to forget that they even exist as well.
While you're at it, using a while loop (counting down, no less) in a case like this mostly just obfuscates the code while gaining nothing in return. For that matter, using a variable name like tot instead of (for example) total or (better) pair_count is kind of silly as well.
So, having gotten bombastic about what you shouldn't do, what would I suggest instead? First, if you're going to use stream >> var type input, try to use it consistently. If you're going to read lines instead, try to do that consistently. In this case, you can use either one, but mixing the two leads to exactly the sort of problem you're having right now. As such, it's best to avoid that whole area if you can (and you almost always can).
For this, I'd use >> throughout, use std::string to hold the strings, and a for loop to execute the fixed number of iterations:
int word_count;
std::cin >> pair_count;
for (int i=0; i<pair_count; i++) {
std::string a, b;
std::cin >> a >> b;
std::cout << a.size() << b.size() << '\n';
}
Unlike the other recommendations you've gotten, this is typesafe (scanf and company don't even try to be), safe from buffer overflows (gets never is, and while scanf and company can be, they aren't when used as the other answers have recommended). It's also shorter and simpler without adding mostly-unexplained patches to cover up the real problems in the code.
If the preceding sounds harsh, I apologize for that. Unfortunately, that's sometimes just about necessary to get the point across, and at least to me, this seems like one of those times.
1. The zeroth commandment: thou shalt not use gets. If you do, you shall surely die (but not as soon as everybody maintaining your code wishes you had).

Answer 2

You should really try using the standard template library for string things:
std::string a, b;
int numberToAsk = 0;
cin >> numberToAsk;
while(numberToAsk!=0) {
cin >> a >> b;
cout << a.size() << ", " << b.size() << endl;
--numberToAsk;
}
(also make sure to use std::vector in stead of plain arrays!)
Also, you can avoid needing to ask for the number of entries upfront by just checking if standard input is still ok; your program will end as soon as you end the input stream (e.g. ctrl+z or F6 on windows, or ctrl+d on linux):
while(cin >> a >> b) {
cout << a.size() << ", " << b.size() << endl;
}

Answer 3

cin>>tot;
This code does not consume '\n' character. So the first gets call reads line between "4" and "\n". To see it you may try input
4abcd
xyz
abcd
bcda
aabc
acaa
Codechef
elfedcc

Answer 4

change cin to scanf works
#include <iostream>
#include <cstring>
#include <stdio.h>
using namespace std;
int main() {
char a[10001],b[10001];
int tot,s1,s2;
scanf("%d\n",&tot);
while(tot!=0) {
gets(a);
gets(b);
s1= strlen(a);
s2= strlen(b);
cout<<s1<<s2<<endl;
tot--;
s1=0;
s2=0;
}
}

Answer 5

Do it this way
scanf("%d ",%t);
For taking in no. of inputs. That space avoids '\n' character that you enter after entering a number input which is taken by first string. Rest of your code can be done as it is.
You need to include cstdio header. #include<cstdio>