gnuplot window does not show

Question

I am trying to initialize the gnuplot using C interface, following this example:

#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
void plot(float xValues[], float yValues[], int NUM_POINTS) {
    char* commandsForGnuplot[] = { "set title \"TITLEEEEE\"", "plot 'data.temp'", "fflush(gnuplotPipe)" };
    FILE* temp = fopen("data.temp", "w");
    FILE* gnuplotPipe = _popen("gnuplot -persistent", "w");
    int i;
    for (i = 0; i < NUM_POINTS; i++)
    {
        fprintf(temp, "%lf %lf \n", xValues[i], yValues[i]); //Write the data to a temporary file
    }

    fclose(temp);

    for (i = 0; i < 3; i++)
    {
        fprintf(gnuplotPipe, "%s \n", commandsForGnuplot[i]); //Send commands to gnuplot one by one.
    }
}

void main(){
    float a[] = {0, 1, 2, 5, 8};
    float b[] = {0, 1, 2, 3, 4};
    plot(a, b, 5);
}

For some reason, the plot does not show up. What I should correct?

Edit

Found out that the prompt window shows the following message:

"'gnuplot' is not recognized as an internal or external command, operable program or batch file."

Edit2 Following @theozh added the path to gnuplot.exe and solved the problem

You may try to close `temp` file before using it with gnuplot — Damien, Jan 14 '21 at 07:22
add the path of `gnuplot.exe` to the Windows environment variable `PATH` or give the full path of `gnuplot.exe` in your `_popen()` command. — theozh, Jan 14 '21 at 07:36
You should always check any `FILE *` variables for `NULL` value before using it. — Gerhardh, Jan 14 '21 at 08:08

score 2 · Accepted Answer · answered Jan 14 '21 at 08:04

Again my comment as answer, according to the SO "rule": no answers in comments. Otherwise this question would continue to appear unanswered.

Either

add the path of gnuplot.exe to the Windows environment variable PATH

or

give the full path of gnuplot.exe in your _popen() command

gnuplot window does not show

1 Answers1