ctype.h

Question 1

What is isalnum()?

int isalnum(int character);

Answer 1

a letter (A to Z or a to z) or a digit (0 to 9)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 2

What is isalpha()?

int isalpha(int character);

Answer 2

a letter (A to Z or a to z)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 3

What is iscntrl()?

int iscntrl(int character);

Answer 3

any control character (0x00 to 0x1F or 0x7F)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 4

What is isdigit()?

int isdigit(int character);

Answer 4

a digit (0 to 9)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 5

What is isgraph()?

int isgraph(int character);

Answer 5

any printing character except for the space character (0x21 to 0x7E)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 6

What is islower()?

int islower(int character);

Answer 6

a lowercase letter (a to z)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 7

What is isprint()?

int isprint(int character);

Answer 7

any printing character (0x20 to 0x7E)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 8

What is ispunct()?

int ispunct(int character);

Answer 8

any punctuation character (any printing character except for space character or isalnum)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 9

What is isspace()?

int isspace(int character);

Answer 9

a whitespace character (space, tab, carriage return, new line, vertical tab, or formfeed)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 10

What is isupper()?

int isupper(int character);

Answer 10

an uppercase letter (A to Z)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 11

What is isxdigit()?

int isxdigit(int character);

Answer 11

a hexadecimal digit (0 to 9, A to F, or a to f)

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.

Question 12

What is tolower()?

int tolower(int character);

Answer 12

If the character is an uppercase character (A to Z), then it is converted to lowercase (a to z)

The to… functions provide a means to convert a single character. If the character matches the appropriate condition, then it is converted. Otherwise the character is returned unchanged.

Example:

    #include
     #include
     #include

    int main(void)
     {
       int loop;
       char string[]="THIS IS A TEST";

  for(loop=0;loop
     string[loop]=tolower(string[loop]);

  printf("%s\n",string);
   return 0;
 }

Question 13

What is toupper()?

int toupper(int character);

Answer 13

If the character is a lowercase character (a to z), then it is converted to uppercase (A to Z)

The to… functions provide a means to convert a single character. If the character matches the appropriate condition, then it is converted. Otherwise the character is returned unchanged.

Example:

#include<ctype.h><br>	 #include<stdio.h><br>	 #include<string.h></string.h></stdio.h></ctype.h>

    int main(void)
     {
       int loop;
       char string[]="THIS IS A TEST";

  for(loop=0;loop<strlen></strlen>         string[loop]=tolower(string[loop]);

  printf("%s\n",string);
   return 0;
 }