Strip numbers from a string in C

Question

I'm looking for a simple solution for stripping numbers from a string. Example: "GA1UXT4D9EE1" => "GAUXTDEE"

The occurrence of the numbers inside the string is erratic hence I cannot rely on functions such as scanf().

I'm new at programming in C. Thanks for any help.

There is no simple solution for string operations in C. :p Post your code! — Christian Graf, Jul 09 '13 at 20:26
This may help http://stackoverflow.com/questions/8044081/how-to-do-regex-string-replacements-in-pure-c — Seano666, Jul 09 '13 at 20:26

score 3 · Answer 1 · answered Jul 09 '13 at 20:27

3

I will give you some tips:

You need to creat a new string.
Iterat over the original string.
Check if the current character is between the ascii values of numbers
If not, add it to the new string.

answered Jul 09 '13 at 20:27

Ran Eldan

1,350
11
25

1

Don't assume ASCII, use [`isdigit`](http://www.cplusplus.com/reference/cctype/isdigit/) – Kninnug Jul 09 '13 at 20:31
@Anton If you want have more fun with coding you can try saving the stripped version of string in the original string. – Pramod Gurav Jul 12 '13 at 10:13

score 1 · Answer 2 · answered Jul 09 '13 at 20:27

1

iterate through the string and check for the ascii value.

for(i = 0; i < strlen(str); i++)
{
  if(str[i] >= 48 && str[i] <= 57)
  {
    // do something
  }
}

answered Jul 09 '13 at 20:27

robin.koch

1,223
1
13
20

3

I do not recommend using bare numbers. Much better to use the appropriate character constants: `if (str[i] >='0' && str[i] <= '9')`... Alternatively, `#include ` and use the `isdigit()` macro. – This isn't my real name Jul 09 '13 at 20:56

score 1 · Accepted Answer · answered Jul 09 '13 at 20:30

char stringToStrip[128];
char stripped[128];
strcpy(stringToStrip,"GA1UXT4D9EE1");

const int stringLen = strlen(stringToStrip);
int j = 0;
char currentChar;

for( int i = 0; i < stringLen; ++i ) {
    currentChar = stringToStrip[i];
    if ((currentChar < '0') || (currentChar > '9')) {
        stripped[j++] = currentChar;
    }
}

stripped[j] = '\0';

score 0 · Answer 4 · answered Jul 09 '13 at 20:31

0

I would agree that walking through would be an easy way to do it, but there is also an easier function to do this. You can use isdigit(). C++ documentation has an awesome example. (Don't worry, this also works in c.)

http://www.cplusplus.com/reference/cctype/isdigit/

answered Jul 09 '13 at 20:31

Owl_Prophet

362
5
15

[http://pubs.opengroup.org/onlinepubs/9699919799/functions/isdigit.html](http://pubs.opengroup.org/onlinepubs/9699919799/functions/isdigit.html) – This isn't my real name Jul 09 '13 at 20:59

score 0 · Answer 5 · answered Jul 09 '13 at 20:58

Here is the code to do it.

int i;
int strLength = strlen(OriginalString);
int resultPosCtr = 0;

char *result = malloc(sizeof(char) * strLength);//Allocates room for string. 

for(i = 0; i < strLength; i++){
    if(!isdigit(OriginalString[i])){
         result[resultPosCtr] = OriginalString[i];
         resultPosCtr++;
    }
}
result[resultPosCtr++] = '\0'; //This line adds the sentinel value A.K.A the NULL Value that marks the end of a c style string.

Everyone has it right.

Create a new char[] A.K.A. C style string.
Iterate over the original string
Check to see if the character at that iteration is a number
if not add to new string

Strip numbers from a string in C

5 Answers5