C Programming - converting a number to hexidecimal and other bases larger then 10

I'm in the middle of writing a program which converts normal base 10 numbers into any base. When you convert to a base larger then 10 it gets a little confusing how to represent those numbers larger than 10. In hexidecimal the numbers 10 through to 15 are represented as A through to F. Here's a function I have written which converts a number in this way, representing larger then 10 numbers into letters up to Z.

//prints a number in a base using symbols for numbers greater than 10

//similar to hexidecimal. Max base is 36

void printInBaseWithUniqueSymbols (int number, int base){

assert(base > 1);

//find out how many units is needed to make the number

//int numberOfUnits = 1;

int units = base;

while (units <= number) {

//numberOfUnits ++;

units = units * base;

}

    //make an array which contains symbols to use from 1 to base

//using a to z for numbers 10 to 36

    char numberArray [base];

for (int i=0; i

if (i<10) {

numberArray[i]=(48+i);

} else {

numberArray[i]= (65 + (i-10));

}

}

//printf("%c", numberArray[1]);

//work out which how many of each unit

    //int i = 0;

    

int result = number;

while (units > 1) {

units = units / base;

int numberOfUnits = result / units;

//printf("%c", numberOfUnits);

char character = numberArray[numberOfUnits];

printf("%c", character);

result = result % units;

        //i++;

}

}

Results:

Type a starting number: Running…
1
Type an end number: 100
Type a base to count in: 16
1 = 1

2 = 2

3 = 3

4 = 4

5 = 5

6 = 6

7 = 7

8 = 8

9 = 9

10 = A

11 = B

12 = C

13 = D

14 = E

15 = F

16 = 10

17 = 11

18 = 12

19 = 13

20 = 14

21 = 15

22 = 16

23 = 17

24 = 18

25 = 19

26 = 1A

27 = 1B

28 = 1C

29 = 1D

30 = 1E

31 = 1F

32 = 20

33 = 21

34 = 22

35 = 23

36 = 24

37 = 25

38 = 26

39 = 27

40 = 28

41 = 29

42 = 2A

43 = 2B

44 = 2C

45 = 2D

46 = 2E

47 = 2F

48 = 30

49 = 31

50 = 32

51 = 33

52 = 34

53 = 35

54 = 36

55 = 37

56 = 38

57 = 39

58 = 3A

59 = 3B

60 = 3C

61 = 3D

62 = 3E

63 = 3F

64 = 40

65 = 41

66 = 42

67 = 43

68 = 44

69 = 45

70 = 46

71 = 47

72 = 48

73 = 49

74 = 4A

75 = 4B

76 = 4C

77 = 4D

78 = 4E

79 = 4F

80 = 50

81 = 51

82 = 52

83 = 53

84 = 54

85 = 55

86 = 56

87 = 57

88 = 58

89 = 59

90 = 5A

91 = 5B

92 = 5C

93 = 5D

94 = 5E

95 = 5F

96 = 60

97 = 61

98 = 62

99 = 63

100 = 64

installing Octave on Mac OS X 10.6 and 10.7

So, just read the wiki here. As it's open source, they havent yet made a pkg installer for it. Apparently, the best thing to do is to use a Package Manager to install it for you.

I've just tried Fink but the website isn't working. Looks like they've moved their website to http://fink.thetis.ig42.org/. Apperantly there's no pkg installer for this either! Here's the download for the binary.

I gave up here and found that MacPorts have an installer.

Installed MacPorts alright, but when I tried to run the command:

sudo port install octave-devel +atlas+docs

It came up with the error not knowing what the command "port" was. I had to type in:

export PATH=/opt/local/bin:/opt/local/sbin:$PATH

One prerequisite is to have xcode installed.

Having done all this, still came up with an error:

Error: Port octave-devel not found

I think it's because we have a proxy server which looks like complicated to add to MacPorts!

Oh well, might just try Matlab! (student version £55!)


....... a little time later......

So I'm now trying at home on OS X 10.7.5

Installed MacPorts
trying to install octave but comes up with:

Error: Port octave not found

Turns out you have to selfupdate MacPort in order for it to sync something or other. Type:

sudo port -v selfupdate

This then came up with the error:

rsync: failed to connect to rsync.macports.org: Connection refused (61)

rsync error: error in socket IO (code 10) at /SourceCache/rsync/rsync-42/rsync/clientserver.c(105) [receiver=2.6.9]

Command failed: /usr/bin/rsync -rtzv --delete-after rsync://rsync.macports.org/release/tarballs/base.tar /opt/local/var/macports/sources/rsync.macports.org/release/tarballs

Exit code: 10

Error: /opt/local/bin/port: port selfupdate failed: Error synchronizing MacPorts sources: command execution failed

Doh! Just did a search and found this. Turns out I have PeerGuardian running. Turned it off and ran selfupdate again which worked fine. So, next I tried installing octave again:

sudo port install octave

--->  Computing dependencies for octave

Error: Dependency 'atlas' not found.

Doh! I read this article which tells how other people are having the same trouble. Looks like one of the sync files on a server must be wrong. selfupdating port at some point will fix it;

sudo port -v selfupdate
sudo port install octave +accelerate +gcc45

What do you know? It worked!!

C Programming - convert number to any base

Just to continue with my programming practice I decided to write a function which takes a number and a base and converts that number to that base.

Here's the function:

//takes a number and a base to work to. It converts (just prints) this number to said base

//base has to be greater then 1

void printInBase(int number, int base) {

    

    assert(base > 1);

    

//find out how many units is needed to make the number

//int numberOfUnits = 1;

int units = base;

while (units <= number) {

//numberOfUnits ++;

units = units * base;

}

    //make an array which will be printed out in the end

    //int numberArray [numberOfUnits];

//work out which how many of each unit

    //int i = 0;

    

int result = number;

while (units > 1) {

units = units / base;

printf("%d", result / units);

result = result % units;

        //i++;

}

 

//prints out array

    //for (int c = 0; c <= numberOfUnits ; c++) {

    //    printf("%d", numberArray[c]);

    //}

}

 Output:

Type a starting number: 1

Type an end number: 30

Type a base to count in: 7

1 = 1

2 = 2

3 = 3

4 = 4

5 = 5

6 = 6

7 = 10

8 = 11

9 = 12

10 = 13

11 = 14

12 = 15

13 = 16

14 = 20

15 = 21

16 = 22

17 = 23

18 = 24

19 = 25

20 = 26

21 = 30

22 = 31

23 = 32

24 = 33

25 = 34

26 = 35

27 = 36

28 = 40

29 = 41

30 = 42

The function fails at counting base 1, but it hurts my brain too much to think about it! Also, to count in a base larger then 10, it's best to put a comma between digits. e.g:

Type a starting number: 1

Type an end number: 30

Type a base to count in: 15

1 = 1,

2 = 2,

3 = 3,

4 = 4,

5 = 5,

6 = 6,

7 = 7,

8 = 8,

9 = 9,

10 = 10,

11 = 11,

12 = 12,

13 = 13,

14 = 14,

15 = 1,0,

16 = 1,1,

17 = 1,2,

18 = 1,3,

19 = 1,4,

20 = 1,5,

21 = 1,6,

22 = 1,7,

23 = 1,8,

24 = 1,9,

25 = 1,10,

26 = 1,11,

27 = 1,12,

28 = 1,13,

29 = 1,14,

30 = 2,0,

This way you can distinguish between the 10's and 20's etc. Might be worth putting this in the function. But also, I could make it convert to hexadecimal? Might require more brain hurt.

Prime Factorisation - programming

Thought I'd test my programming skills by making a program which tells you the prime factorisation of a number or range of numbers. i.e:

4 = 2 x 2
10 = 2 x 5
20 = 2 x 2 x 5

etc...

Here's the code which works it out for a series of numbers:

//

//  main.c

//  printInPrimeFactors

//

//  Created by Monkey on 10/03/2013.

//  Copyright (c) 2013 Monkey. All rights reserved.

//

#include

#define TRUE 1

#define FALSE 0

int isPrime (int number);

int printInPrimeFactors (int number);

int main(int argc, const char * argv[])

{

    //scan in a number

    int startNumber = 0;

    printf("Type a starting number: ");

    scanf("%d", &startNumber);

    

    int endNumber = 0;

    printf("Type an end number: ");

    scanf("%d", &endNumber);

    

    //find the prime factors of range of numbers

    for (int i=startNumber; i<=endNumber; i++) {

        printInPrimeFactors(i);

    }

    

        return 0;

}

int printInPrimeFactors (int number) {

    //printf("finding the prime factors of %d.....\n", number);

    

    //if it's a prime just print it and return to main

    if (isPrime(number)) {

        printf("%d\n", number);

        return 0;

    }

    

    //for nice formatting I'm printing the number =

    printf("%d = ", number);

    

    //testing to find a factor of the number, which is also prime

    for (int i =2; i < number; i++) {

        if (number %i == 0 && isPrime(i)) {

            //printf("a prime factor of %d is %d\n", number, i);

            

            //testing to see how many times the number can be divided by 'i' and printing i each time

            //printf("testing to see how many times %d can divide by %d\n", number, i);

            int result = number;

            while (result % i == 0) {

                printf("%d x ", i);

                result = result / i;

            }

            

            //print an extra line to make it look nice

            //printf("\n");

        }

    }

    

    //print new line for next number

    printf("1\n");

    return 0;

}

//a function which returns true or false if number is prime

int isPrime (int number) {

    //printf("testing to see if %d is a prime\n", number);

    int prime = TRUE;

    

    //test to see if it is divisible by any other numbers

    for (int i = 2; i < number; i++) {

        if (number %i ==0) {

            prime = FALSE;

            //printf("%d is not a prime number\n", i);

            return prime;

        }

    }

    return prime;

}

output:

Type a starting number: 100

Type an end number: 120

100 = 2 x 2 x 5 x 5 x 1

101

102 = 2 x 3 x 17 x 1

103

104 = 2 x 2 x 2 x 13 x 1

105 = 3 x 5 x 7 x 1

106 = 2 x 53 x 1

107

108 = 2 x 2 x 3 x 3 x 3 x 1

109

110 = 2 x 5 x 11 x 1

111 = 3 x 37 x 1

112 = 2 x 2 x 2 x 2 x 7 x 1

113

114 = 2 x 3 x 19 x 1

115 = 5 x 23 x 1

116 = 2 x 2 x 29 x 1

117 = 3 x 3 x 13 x 1

118 = 2 x 59 x 1

119 = 7 x 17 x 1

120 = 2 x 2 x 2 x 3 x 5 x 1

after all that I found this nice website which basically does the same!