Tolower
Syntax
int tolower ( int c );
Description
Convert uppercase letter to lowercase
Converts c to its lowercase equivalent if c is an uppercase letter and has a lowercase equivalent. If no such conversion is possible, the value returned is c unchanged.
Notice that what is considered a letter may depend on the locale being used; In the default "C" locale, an uppercase letter is any of: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z, which translate respectively to: a b c d e f g h i j k l m n o p q r s t u v w x y z.
In other locales, if an uppercase character has more than one correspondent lowercase character, this function always returns the same character for the same value of c.
In C++, a locale-specific template version of this function (tolower) exists in header <locale>.
Parameters
- c
- Character to be converted, casted to an int, or EOF.
Return Value
The lowercase equivalent to c, if such value exists, or c (unchanged) otherwise.
The value is returned as an int value that can be implicitly casted to char.
Example
| Source | Run |
|---|---|
#include <stdio.h>
#include <ctype.h>
int isVowel(char c);
int main(int argc, char *argv[])
{
FILE *pFile = NULL;
int c = 0;
int countVowels = 0;
pFile = fopen("pets", "r");
if (pFile==NULL) perror("Error opening file\n");
else {
do {
c = fgetc(pFile);
if(isVowel(c)) countVowels++;
} while (c != EOF);
printf("The file contains %d vowels\n", countVowels);
fclose(pFile);
}
return 0;
}
int isVowel(char c)
{
c = tolower(c);
if (c=='a' || c== 'e' || c=='i' || c=='o' || c=='u' || c=='y')
return 1;
else
return 0;
}
|
$ cat pets You have 3 pets and prefer cats. $ ./code The file contains 10 vowels |