C, how to change color of text with user input?

Question

In C language, there is this function

system("Color x")

Which changes the color of console text. However i've been wondering how to use this function with user input, by entering desired color, for example:

char color;
printf("Enter color: "); //user enters A/B/C etc.
scanf(" %c", &color);
system("Color %c", color);

Build a string to pass to system. `char cmd[42]; sprintf(cmd, "Color %c", color); system(cmd);` — Weather Vane, Oct 16 '22 at 11:34
I recommend looking into ANSI escape sequences. This approach is slow and windows-only. — LordMZTE, Oct 16 '22 at 12:13

Yun · Accepted Answer · 2022-10-16T12:36:48.100

The system command doesn't accept parameters in the same way the print family of commands does (i.e. a format string followed by a variable argument list with variable names). The solution is to build the desired string first using sprintf. First, allocate memory for the target string:

char cmd[8]; // E.g. "Color x" has 8 chars when including the null terminator.

Then, use sprintf to combine the format string and variable, and write the result to cmd:

sprintf(cmd, "Color %c", color);

Finally, call system using the string just written to:

system(cmd);

This is assuming that you want to use this method for changing colors. For a better approach, see here.

C, how to change color of text with user input?

1 Answers1