c, delete words which contain digits from a string - c

Question

I need to delete all words that contain digits from the string.
E.g. if input is abdgh 67fgh 32ghj hj dfg43 11 fg, output should be abdgh hj fg.
I thought of using while( text[i] != ' '), but I don't know how to continue it for the rest of the string (after the first whitespace).
I don't have any other idea, and couldn't find anything by googling. Please, help me!

Answer 1

Here, i gave it a try. Works just fine for me. I tried to explain the logic throughout the code via comments. Hope it helps.
#include <stdio.h>
#include <string.h>
int containsNum(char * str);
int main()
{
char str[] = "abdgh 67fgh 32ghj hj dfg43 11 fg"; // input string
char newstr[100] = ""; //new string to create with filtered data
char * pch; //temp string to use in strtok
printf("given string : %s\n",str );
pch = strtok (str," ");
while (pch != NULL)
{
if(!containsNum(pch))// creation of new string with strcat
{ // if the current word not contains any number
strcat(newstr,pch);
strcat(newstr," "); //adding a space between words for readability
}
pch = strtok (NULL, " ");
}
printf("modified string : %s\n", newstr );
return 0;
}
//function containsNum
//gets a string and checks if it has any numbers in it
//returns 1 if so , 0 otherwise
int containsNum(char * str)
{
int i,
size =strlen(str),
flag=0;
for(i=0; i<size ; ++i)
{
if((int)str[i] >=48 && (int)str[i] <=57 ){
flag =1;
break;
}
}
return flag;
}
Regards

Answer 2

Algorithm:
1-You will have to break your input string into smaller components which are also called as tokens. For example: for the string abdgh 67fgh 32ghj hj dfg43 11 fg the tokens could be abdgh, 67fgh, 32ghj, hj, dfg43, 11 and fg.
2- These smaller strings or tokens can be formed using the strtok function which is defined as
char * strtok ( char * str, const char * delimiters );. Thestr in the first argument is the input sting which in the code presented below is string1. The second argument called the delimiters is what actually defines when to divide the input string into smaller pieces(tokens).
For instance, a whitespace as a delimiter will divide the input string whenever a whitespace is encountered, which is how the string is being divided in the code.
3-Since, your program needs to delete those words in the input string which contain digits we can use the isdigit() function to check exactly that.
WORKING CODE:
#include <cstring>
#include <ctype.h>
#include<stdio.h>
int main ()
{
char output[100]="";
int counter;
int check=0; /* An integer variable which takes the value of "1" whenever a digit
is encountered in one of the smaller strings or tokens.
So, whenever check is 1 for any of the tokens that token is to be ignored, that is,
not shown in the output string.*/
char string1[] = "abdgh 67fgh 32ghj hj dfg43 11 fg";
char delimiters[] = " ";//A whitespace character functions as a delimiter in the program
char * token;//Tokens are the sub-strings or the smaller strings which are part of the input string.
token=strtok(string1,delimiters);/*The first strktok call forms the first token/substring which for the input
given would be abdgh*/
while(token!=NULL)/*For the last substring(token) the strtok function call will return a NULL pointer, which
also indicates the last of the tokens(substrings) that can be formed for a given input string.
The while loop finishes when the NULL pointer is encountered.*/
{
for(counter=0;counter<=strlen(token)-1;counter++)/*This for loop iterates through each token element.
Example: In case of abdgh, it will first check for 'a',
then 'b', then 'd' and so on..*/
{
if(isdigit((int)token[counter])>0)/*This is to check if a digit has been encountered inside a token(substring).
If a digit is encountered we make check equal to 1 and break our loop, as
then that token is to be ignored and there is no real need to iterate
through the rest of the elements of the token*/
{
check=1;
break;
}
}
if(check==1) /* Outside the for loop, if check is equal to one that means we have to ignore that token and
it is not to be made a part of the output string. So we just concatenate(join) an
empty string ( represented by " " )with the output string*/
{
strcat(output,"");
check=0;
}
else /*If a token does not contain any digit we simply make it a part of the output string
by concatenating(joining) it with the output string. We also add a space for clarity.*/
{
strcat(output,token);
strcat(output," ");
}
token = strtok( NULL, delimiters ); /*This line of code forms a new token(substring) every time it is executed
inside the while loop*/
}
printf( "Output string is:: %s\n", output ); //Prints the final result
return 0;
}

Answer 3

#include <stdio.h>
#include <ctype.h>
#include <stdbool.h>
char *filter(char *str){
char *p, *r;
p = r = str;
while(*r){
char *prefetch = r;
bool contain_digit = false;
while(!isspace(*prefetch) && *prefetch){
if(contain_digit)
++prefetch;
else if(isdigit(*prefetch++))
contain_digit = true;
}
if(contain_digit){
r = prefetch;
}else {
while(r < prefetch){
*p++ = *r++;
}
}
if(!*r)
break;
if(p[-1] == *r)
++r;
else
*p++ =*r++;
}
*p = '\0';
return str;
}
int main(void) {
char text[] = "abdgh 67fgh 32ghj hj dfg43 11 fg";
printf("%s\n", filter(text));//abdgh hj fg
return 0;
}