Fast C++ String Output -

i have program outputs data fpga. since data changes extremely fast, i'm trying increase speed of program. right printing data this

for (int = 0; < 100; i++) {     printf("data: %d\n",getdata(i)); } 

i found using 1 printf increases speed

printf("data: %d \n data: %d \n data: %d \n",getdata(1),getdata(2),getdata(3)); 

however, can see, messy , can't use loop. tried concatenating strings first using sprintf , printing out @ once, it's slow first method. suggestions?

edit: i'm printing file first, because realized console scrolling issue. still slow. i'm debugging memory controller external fpga, closer real speed better.

if writing stdout, might not able influence all.

otherwise, set buffering

• setvbuf http://en.cppreference.com/w/cpp/io/c/setvbuf
• std::nounitbuf http://en.cppreference.com/w/cpp/io/manip/unitbuf
• and untie input output streams (c++) http://en.cppreference.com/w/cpp/io/basic_ios/tie
• std::ios_base::sync_with_stdio(false) (thanks @dietmar)

now, boost karma known pretty performant. however, i'd need know more input data.

meanwhile, try buffer writes manually: live on coliru

#include <stdio.h>  int getdata(int i) { return i; }  int main() {     char buf[100*24]; // or other nice, large enough size     char* const last = buf+sizeof(buf);     char* out = buf;      (int = 0; < 100; i++) {         out += snprintf(out, last-out, "data: %d\n", getdata(i));     }      *out = '\0';     printf("%s", buf); }