C - How to add a float variable to a string -

i've got variable contains floating number, how do adding string?

something this:

int main() {     char postdata[] = "field1=";     float mynumber = 123.12;     postdata = postdata + mynumber;     return 0; } 

i want end result "field1=123.1"

it doesnt seem easy postdata + mynumber :(

use sprintf:

char buffer[32]; sprintf(buffer, "%s%f", postdata, mynumber); 

if need one-digit precision:

char buffer[32]; sprintf(buffer, "%s%.1f", postdata, mynumber); 

here working example.