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  1. #include <stdio.h>
  2. #include <stdarg.h>
  3. int prefix_printf(const char* fmt, ...)
  4. {
  5. printf("prefix ");
  6.  
  7. va_list args;
  8. va_start(args, fmt);
  9.  
  10. int result = vprintf(fmt, args);
  11. va_end(args);
  12. return result;
  13. }
  14.  
  15.  
  16. int main(void) {
  17. prefix_printf("No number\n");
  18. prefix_printf("Number = %d\n", 20);
  19. return 0;
  20. }
  21.  
Success #stdin #stdout 0.01s 5536KB
stdin
Standard input is empty
stdout
prefix No number
prefix Number = 20