Reputation: 41
Below is my c++ program to multiply two strings (Integers in strings) and produce the integer result in string. I believe it is due to cout flush problem. Can someone explain how to print the value without endl or any text string just before printing the answer.
#include <iostream>
using namespace std;
string multiply (string s1, string s2)
{
char str[10];
string ans="";
int m=s1.length();
int n=s2.length();
if (!s1.compare("0") || !s2.compare("0"))
return "0";
int *res = new int[m + n];
for (int i = m - 1; i >= 0; i--)
{
for (int j = n - 1; j >= 0; j--)
{
res[m + n - i - j - 2] += (s1[i] - '0') * (s2[j] - '0');
res[m + n - i - j - 1] += res[m + n - i - j - 2] / 10;
res[m + n - i - j - 2] %= 10;
}
}
for (int i = m + n - 1; i >= 0; i--)
{
if (res[i] != 0)
{
for (int j = i; j >= 0; j--)
{
sprintf(str,"%d", res[j]);
ans+=str;
}
return ans;
}
}
}
int main() {
cout << multiply("0", "0"); // Doesn't work - prints nothing.
/**cout << multiply("0", "0") << endl; //works!! This prints "0" correctly **/
return 0;
}
Upvotes: 4
Views: 5151
Reputation: 1
You should notice that std::endl
includes flushing the output stream. As from the reference documentation:
Inserts a newline character into the output sequence
os
and flushes it as if by callingos.put(os.widen('\n'))
followed byos.flush()
.
So if you flush cout
after printing in your example
cout << multiply("0", "0");
cout.put(cout.widen('\n'));
cout.flush();
you would see the result printed Live Demo.
For more information about flushing and what it actually means for buffered output read here please std::ostream::flush()
.
Upvotes: 6