Is this something common to all programming languages? Doing multiple print followed by a println seems faster but moving everything to a string and just printing that seems fastest. Why?
EDIT: For example, Java can find all the prime numbers up to 1 million in less than a second – but printing then all out each on their own println can take minutes! Up to a 10 billion can hours to print!
EX:
package sieveoferatosthenes;
public class Main {
public static void main(String[] args) {
int upTo = 10000000;
boolean primes[] = new boolean[upTo];
for( int b = 0; b < upTo; b++ ){
primes[b] = true;
}
primes[0] = false;
primes[1] = false;
int testing = 1;
while( testing <= Math.sqrt(upTo)){
testing ++;
int testingWith = testing;
if( primes[testing] ){
while( testingWith < upTo ){
testingWith = testingWith + testing;
if ( testingWith >= upTo){
}
else{
primes[testingWith] = false;
}
}
}
}
for( int b = 2; b < upTo; b++){
if( primes[b] ){
System.out.println( b );
}
}
}
}
Best Answer
println
is not slow, it's the underlyingPrintStream
that is connected with the console, provided by the hosting operating system.You can check it yourself: compare dumping a large text file to the console with piping the same textfile into another file:
Reading and writing are similiar and proportional to the size of the file (O(n)), the only difference is, that the destination is different (console compared to file). And that's basically the same with
System.out
.The underlying OS operation (displaying chars on a console window) is slow because