VC++库函数大全(国外英语资料).docVIP

VC++库函数大全(国外英语资料) Appendix 2 commonly used library functions Microsoft C provides a large number of library functions for application designers, whose functions cover all aspects of programming and must be mastered by every programmer. In this appendix, we choose the library functions which are more commonly used for reference. To save space, we only list functional prototypes and simple functional descriptions. If you are in use, you still have questions about the functions, parameters, settings, and return values of a library function. You can see the instructions in the MSDN directly. 1. classification library functions, the prototype is in the header file ctype.h. This set of library functions is actually macro with arguments. Prototype: int isalpha (int c); Function: returns 0 if C returns a non - 0 value for the letter. Prototype: int isDigit (int c); Function: if C returns no 0 value for digits, otherwise it returns. Prototype: int isalnum (int c); Function: if C is a letter or digit, returns no 0 value, otherwise returns 0. Prototype: int islower (int c); Int isupper (int c); Function: if C is lowercase (uppercase), the letter returns no 0 value, otherwise returns 0. Prototype: int isprint (int c); Function: if C is printable characters (including letters, numbers, spaces, and various symbols, etc.), returns no 0 value, or returns 0. Prototype: int isspace (int c); Function: if C is a space, tab, carriage return, line feed, and so on, returns a non - 0 value, or returns 0. Prototype: int tolower (int ch); Int toupper (int ch); Function: converts characters to lowercase or uppercase characters. 2. directory operation function, used in the program processing file directory system, the prototype is in the header file direct.h. Prototype: int _chdir (const char *dirname); Function: change the current directory. Prototype: int _chdrive (int drive); Function: change the current drive. Prototype: char *_getcwd (char, *buffer, int, maxlen); Function: read the curre