frequency analysis

[Pete]

I need to write a program to do a frequency analysis on a string of text.
Firstly I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.
Thankyou

 

[Emmanuel Delahaye]

<...> I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

static char const Alphabet[26] = "abcdefghijklmnopqrstuvwxyz";

But if you want A to Z :

static char const Alphabet[26] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

Beware, in both cases, despite the appearences, 'Alphabet' is /not/ a string
literal. str*() functions won't work. If you want string literals, just
remove the size:

static char const Alphabet[] = "abcdefghijklmnopqrstuvwxyz";
or
static char const Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

 

[Allin Cottrell]

I need to write a program to do a frequency analysis on a string of text.
Firstly I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

char Alphabet[26];
int i;

for (i=0; i<26; i++) Alphabet = 'a' + i;

There are also isalpha(), islower() and isupper() to consider
(#include <ctype.h>).

 

[Emmanuel Delahaye]

or is there another way to represent the alphabet characters.

char Alphabet[26];
int i;

for (i=0; i<26; i++) Alphabet = 'a' + i;

Wrong advice. The alphabetic character values don't have to be consecutive in
C.

 

[Bertrand Mollinier Toublet]

I need to write a program to do a frequency analysis on a string of text.
Firstly I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

char Alphabet[26];
int i;

for (i=0; i<26; i++) Alphabet = 'a' + i;

This is plain wrong. There is no guarantee whatsoever that alphabetic
characters are consecutive nor in ascending order.

 

[Jeff]

I need to write a program to do a frequency analysis on a string of text.
Firstly I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

char Alphabet[26];
int i;

for (i=0; i<26; i++) Alphabet = 'a' + i;

There are also isalpha(), islower() and isupper() to consider
(#include <ctype.h>).

The C standard said

5.2.1 Character sets
"The values of the members of the execution character set are
implementation-defined."

Your teacher may told you that we can increase the 'A' char(65) to get 'B'
char(66), but it is not always correct. The characters defined by ASCII is
consecutive, but in C, it is 'implementation-defined'.

 

[Allin Cottrell]

I need to write a program to do a frequency analysis on a string of

text.

Firstly I need to get the alphabet A to Z for comparison but I'm not

sure

how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

char Alphabet[26];
int i;

for (i=0; i<26; i++) Alphabet = 'a' + i;

There are also isalpha(), islower() and isupper() to consider
(#include <ctype.h>).

The C standard said

5.2.1 Character sets
"The values of the members of the execution character set are
implementation-defined."

Your teacher may told you that we can increase the 'A' char(65) to get 'B'
char(66), but it is not always correct. The characters defined by ASCII is
consecutive, but in C, it is 'implementation-defined'.

You're right. I recalled that the standard guarantees that the
digits '0' through '9' have consecutive numerical values and incorrectly
generalized this to the Latin alphabet.

Allin Cottrell

 

[Richard Heathfield]

I need to write a program to do a frequency analysis on a string of text.
Firstly I need to get the alphabet A to Z for comparison but I'm not sure
how to go about this.

Is the following the only way to do it:

Alphabet[26] = {'a','b','c',...,'z'};

or is there another way to represent the alphabet characters.

static const char lower[] = "abcdefghijklmnopqrstuvwxyz";
static const char upper[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

But why restrict yourself to letters?

Here's a little frequency counter that counts /everything/, provided
UCHAR_MAX isn't too huge.

#include <limits.h>
#include <stdio.h>

int main(void)
{
unsigned long Count[UCHAR_MAX + 1] = {0};
int ch = 0;
while((ch = getchar()) != EOF)
{
++Count[ch];
}

/* do any output you wanted right here */

return 0;
}

 

[Ben Pfaff]

But if you want A to Z :

static char const Alphabet[26] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

Beware, in both cases, despite the appearences, 'Alphabet' is /not/ a string
literal.

str*() functions won't work. If you want string literals, just
remove the size:

static char const Alphabet[] = "abcdefghijklmnopqrstuvwxyz";

This is an abuse of the term "string literal", which is defined
in C99 6.4.5#2:

A character string literal is a sequence of zero or more
multibyte characters enclosed in double-quotes, as in "xyz".

"abcdefghijklmnopqrstuvwxyz" is a string literal.
`Alphabet' is merely a string.