Tcl_GetInt expects src to consist of a collection of integer digits, optionally signed and optionally preceded and followed by white space. If the first two characters of src after the optional white space and sign are “0x” then src is expected to be in hexadecimal form; otherwise, if the first such characters are “0o” then src is expected to be in octal form; otherwise, if the first such characters are “0b” then src is expected to be in binary form; otherwise, if the first such character is “0” then src is expected to be in octal form; otherwise, src is expected to be in decimal form.
Tcl_GetDouble expects src to consist of a floating-point number, which is: white space; a sign; a sequence of digits; a decimal point “.”; a sequence of digits; the letter “e”; a signed decimal exponent; and more white space. Any of the fields may be omitted, except that the digits either before or after the decimal point must be present and if the “e” is present then it must be followed by the exponent number. If there are no fields apart from the sign and initial sequence of digits (i.e., no decimal point or exponent indicator), that initial sequence of digits should take one of the forms that Tcl_GetInt supports, described above. The use of “,” as a decimal point is not supported nor should any other sort of inter-digit separator be present.
Tcl_GetBoolean expects src to specify a boolean value. If src is any of 0, false, no, or off, then Tcl_GetBoolean stores a zero value at *intPtr. If src is any of 1, true, yes, or on, then 1 is stored at *intPtr. Any of these values may be abbreviated, and upper-case spellings are also acceptable.