C language: write to file without buffering [duplicate]

Question

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Why does printf not flush after the call unless a newline is in the format string? (10 answers)

Closed 9 years ago.

I have opened a file for writing some data to a file, but it keeps buffering and won't write anything to the file until the program ends. How can I skip the buffering process and write directly to the file.

My code:

fprintf (fp, "# Step: %d  %f\n", ntot, eDiff);
for(i=0; i<nType; i++)  
    fprintf (fp, "%s  %f %f\n",param[i].cTypes, param[i].eps, param[i].sigma);
fprintf(fp, "#  ============\n");

Answer 1

Use the fflush() function on the stream:

fflush( fp );