scanf - double value cant read by fscanf in c -

# include <stdio.h> # include <io.h> # include <stdlib.h> int main(int argc,char *argv[]){    file *tfptr;     int accno;     double balance;     if((tfptr=fopen("trans.dat","w"))==null){ //check file trans.dat existed or not         printf("cannot open file. \n");         exit(1);     }     fscanf(stdin,"%d%f",&accno,&balance);/* read keyboard */     fprintf(tfptr,"%d %f",accno,balance);/* write file */     fclose(tfptr); //close file trans.dat     if((tfptr=fopen("trans.dat","r"))==null){ //check file trans.dat file existed or not         printf("cannot open file. \n");         exit(1);     }     fscanf(tfptr,"%d%f",&accno,&balance);/* read file  */     fprintf(stdout,"%d %f",accno,balance);/* write screen */     return 0; } 

output:

12  2.3 12   0.000000 -------------------------------- process exited return value 0 press key continue . . . 

the "%f" format behaves differently between scanf , printf.

for scanf (and family) "%f" reads float variable, not double. if want read double need "%lf" format scanf.