scanning from an input file in C until reaching a certain character (#)?

问题

Simple question:

If i have a line in an input file that looks looks like:

Hello#Great#Day#Today

how can I scan in each word individually as its own array, in other words tell C to stop scanning when it reaches the # character and then go in the next iteration of the loop to scan the next word as a separate array?

回答1:

This is assuming you are reading through stdin. Definitely take a look at @Whoz kick start approach as well (very similar to this).

What you would want to do is create a dynamic array and populate it with every byte read through stdin. You would then want to create an array of character pointers that will point to the first character in every "word", where you define a word as every character before a '#' character (delimiter). You would then iterate through that array of characters and populate the array of character pointers with the memory addresses of the first character in each word.

回答2:

Use strtok() to tokenize your input by the specified character.

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

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

回答3:

In two stages, I have used something like this:

#include <ansi_c.h>

//tokenizing a string
int GetCount(char *in, char *delim, int *m);
int GetStrings(char *in, char *delim, int count, char **out);  


void main(void)
{
    int count, maxlen, i;
    char inpString[]={"Hello#Greatest#Day#Today"};
    char *resultBuf[10];

    //get a count of strings to store
    count = GetCount(inpString, "#", &maxlen);

    for(i=0;i<10;i++)
    {
        resultBuf[i] = calloc(maxlen+1, sizeof(char));  
    }

    //Store strings in arrays
    GetStrings(inpString, "#", count, resultBuf);

    for(i=0;i<count;i++)
    {
        printf("%s\n", resultBuf[i]);
        free(resultBuf[i];
    }             

}
     //Gets count of tokens (delimited strings)
int GetCount(char *in, char *delim, int *m)
{
    char *buf=0;
    char temp1[10]={0};
    char *inStr;
    int count = 0;
    int max = 0, keepMax = 0;
    if(in)
    {

        inStr = calloc(strlen(in)+1, sizeof(char));
        strcpy(inStr, in);
        if(strlen(inStr) > 1)
        {
            count = 0;
            buf = strtok(inStr, delim);
            while(buf)
            {
                strcpy(temp1, buf);
                max = strlen(temp1);
                (max > keepMax)?(keepMax = max):(keepMax == keepMax);
                count++;
                buf = strtok(NULL, delim);
            }
            *m = keepMax;
        }
        free(inStr);
    }
    return count;
}
     //Gets array of strings
int GetStrings(char *in, char *delim, int count, char **out)
{
    char *buf=0;
    char *inStr;
    int i = 0;
    if(in)
    {

        inStr = calloc(strlen(in)+1, sizeof(char));
        strcpy(inStr, in);
        if(strlen(inStr) > 1)
        {
            buf = strtok(inStr, delim);
            while(buf)
            {
                strcpy(out[i], buf);
                buf = strtok(NULL, delim);
                i++;
            }
        }
        free(inStr);
    }
    return 0;
}

来源：https://stackoverflow.com/questions/18191379/scanning-from-an-input-file-in-c-until-reaching-a-certain-character

标签

arrays

loops

input

terminate