I am running the following code on a Sun Solaris OS 5.7 machine.
I am compiling it with both g++ 2.95 and g++ 3.3.2, using the command:
g++ -O3 -o z z.cc
where z.cc is the following:
#include <iostream> #include <fstream> #include <iomanip>
using namespace std;
main(int argc, char** argv) {int i = 1; double d1 = 2.3; double d2 = 3.4;
ofstream ofstr("zout"); for (int counter = 0; counter < 300000; counter++) {
ofstr << i << d1 << d2 << '\n';
}ofstr.close();
}
for g++ 2.95, the executable is 786 kilobytes, and the job takes 2.3 seconds to run
for g++ 3.32, the executable is only 13 kilobytes, but the job takes 9.5 seconds to run
Thus g++ 2.95 is 4 times faster than g++ 3.3.2.
Is this normal?
When I try using <cstdio> instead of <iostream>:
#include <cstdio>
using namespace std;
main(int argc, char** argv) {int i = 1; double d1 = 2.3; double d2 = 3.4;
FILE* ofstr = fopen("zout", "w"); for (int counter = 0; counter < 300000; counter++) {
fprintf(ofstr, "%d%.1f%.1f\n", i, d1, d2);
}fclose(ofstr);
}
for g++ 2.95. the executable is only 6 kilobytes, but takes 3.4 seconds to run
for g++ 3.32, the executable is only 7 kilobytes, but takes only 2.3 seconds to run
Summary:
for g++ 2.95, the <iostream> version produces a large executable, but it runs even quicker than the <cstdio> version
for g++ 3.3.2, the <iostream> version produces a similar size executable as the <cstdio> version, but runs EXTREMELY slow (4 times slower than the g++ 2.95 <iostream> version or the g++ 3.3.2 <cstdio> version)
I would like to use the <iostream> libraries for g++ 3.3.2, but how can I speed up the execution time?
I tried compiling the g++ 3.3.2 <iostream> version using the -static keyword, but it only took a second
of the execution time while creating an enormous 6000 kilobyte executable.
Any suggestions?
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