Provide the code to do the following:

1. Convert lower-case to upper case, no change to other characters?

char array[] = "abcde";

2. Code to replace all "white space" with an underscore?

char array[] = "a b\fc d e\tf\vg";

3. Code to skip white space, convert ASCII digits to a number until non-digit encountered, and output the number?

char array[] = "1 2\f3 4 5\t6\v7";