tolower() ctype Macro tolower() Convert characters to lower case #include <ctype.h> int tolower(c) int c; tolower converts the letter c to lower case. tolower returns c converted to lower case. If c is not a letter or is already lower case, then tolower returns it unchanged. ***** Example ***** The following example demonstrates tolower and toupper. It reverses the case of every character in a text file. #include <ctype.h> #include <stdio.h> main() { FILE *fp; int ch; int filename[20]; printf("Enter name of file to use: "); fflush(stdout); gets(filename); if ((fp = fopen(filename,"r")) != NULL) { while ((ch = fgetc(fp)) != EOF) putchar(isupper(ch) ? tolower(ch) : toupper(ch)); } else printf("Cannot open %s.\n", filename); } ***** See Also ***** ctype, toupper() COHERENT Lexicon Page 1