The number is converted to a string of the form "-d.dddE+ddd" or " -d.ddde+ddd " , where each "d" indicates a digit (0-9). ...

The number is converted to a string of the form "-d.dddE+ddd" or " -d.ddde+ddd " , where each "d" indicates a digit (0-9). The string starts with a minus sign if the number is negative. One digit always precedes the decimal point. The precision specifier indicates the desired number of digits after the decimal point.