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in Technique[技术] by (71.8m points)

Split string in C every white space

I want to write a program in C that displays each word of a whole sentence (taken as input) at a seperate line. This is what i have done so far:


void manipulate(char *buffer);
int get_words(char *buffer);

int main(){
    char buff[100];

    printf("sizeof %d
strlen %d
", sizeof(buff), strlen(buff));   // Debugging reasons

    bzero(buff, sizeof(buff));

    printf("Give me the text:
");
    fgets(buff, sizeof(buff), stdin);

    manipulate(buff);
    return 0;
}

int get_words(char *buffer){                                        // Function that gets the word count, by counting the spaces.
    int count;
    int wordcount = 0;
    char ch;

    for (count = 0; count < strlen(buffer); count ++){
        ch = buffer[count];
        if((isblank(ch)) || (buffer[count] == '')){                   // if the character is blank, or null byte add 1 to the wordcounter
            wordcount += 1;
        }
    }
    printf("%d

", wordcount);
    return wordcount;
}

void manipulate(char *buffer){
    int words = get_words(buffer);
    char *newbuff[words];
    char *ptr;
    int count = 0;
    int count2 = 0;
    char ch = '
';

    ptr = buffer;
    bzero(newbuff, sizeof(newbuff));

    for (count = 0; count < 100; count ++){
        ch = buffer[count];
        if (isblank(ch) || buffer[count] == ''){
            buffer[count] = '';
            if((newbuff[count2] = (char *)malloc(strlen(buffer))) == NULL) {
                printf("MALLOC ERROR!
");
                exit(-1);
            }
            strcpy(newbuff[count2], ptr);
            printf("
%s
",newbuff[count2]);
            ptr = &buffer[count + 1];
            count2 ++;
        }
    }
}

Although the output is what i want, i have really many black spaces after the final word displayed, and the malloc() returns NULL so the MALLOC ERROR! is displayed in the end. I can understand that there is a mistake at my malloc() implementation but i do not know what it is.

Is there another more elegant - generally better way to do it?

Thanks in advance.

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by (71.8m points)

http://www.cplusplus.com/reference/clibrary/cstring/strtok/

Take a look at this, and use whitespace characters as the delimiter. If you need more hints let me know.

From the website:

char * strtok ( char * str, const char * delimiters );

On a first call, the function expects a C string as argument for str, whose first character is used as the starting location to scan for tokens. In subsequent calls, the function expects a null pointer and uses the position right after the end of last token as the new starting location for scanning.

Once the terminating null character of str is found in a call to strtok, all subsequent calls to this function (with a null pointer as the first argument) return a null pointer.

Parameters

  • str
    • C string to truncate.
    • Notice that this string is modified by being broken into smaller strings (tokens). Alternativelly [sic], a null pointer may be specified, in which case the function continues scanning where a previous successful call to the function ended.
  • delimiters
    • C string containing the delimiter characters.
    • These may vary from one call to another.

Return Value

A pointer to the last token found in string. A null pointer is returned if there are no tokens left to retrieve.

Example

/* strtok example */
#include <stdio.h>
#include <string.h>

int main ()
{
  char str[] ="- This, a sample string.";
  char * pch;
  printf ("Splitting string "%s" into tokens:
",str);
  pch = strtok (str," ,.-");
  while (pch != NULL)
  {
    printf ("%s
",pch);
    pch = strtok (NULL, " ,.-");
  }
  return 0;
}

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