CODEWITHSUNDEEP
cstringfile-io
Xara
Xara

Reputation: 9098

File reading in C from one specific character to another

I want to read a line from file in C. Eg in file I have following data

"It was a good

day

but suddenly
everything"

Rightnow, my code just reads line by line but as mentioned in above example I want to read data from the starting inverted commas (") till the ending inverted commas (") and then write that whole string (like "It was a good day but suddenly everything") into another file. i only need help in reading these above lines from starting inverted commas till ending inverted commas. Please guide me which functions in C will help me to do that.

Rightnow, I am just reading data line by line

FILE *file = fopen ( filename, "r" );

 if (file != NULL )
  {
   char line [1000];
   while(fgets(line,sizeof line,file)!= NULL) /* read a line from a file */
    {
    //do something
     }
    }

Upvotes: 0

Views: 2615

Answers (4)

BLUEPIXY
BLUEPIXY

Reputation: 40145

#include <stdio.h>

char *read_quoted_string(char outbuff[], FILE *fp){
    int ch, i;
    while(EOF!=(ch=fgetc(fp)))
        if(ch == '"') break;

    for(i=0;EOF!=(ch=fgetc(fp));++i){
        if(ch == '"') break;
        outbuff[i] = ch;
    }
    outbuff[i]='\0';
    return outbuff;
}

int main(void){
    FILE *file = fopen("data.txt", "r" );

    if (file != NULL ){
        char buff [1000];
        printf("%s", read_quoted_string(buff, file));

        fclose(file);
    }
    return 0;
}

Also repeats

    if (file != NULL ){
        int i=1;//sequence number
        char buff [1000];
        while(*read_quoted_string(buff, file)){//empty is "" (*"" == '\0')
            printf("%2d:%s\n", i++, buff);
        }
        fclose(file);
    }

Upvotes: 3

Midhun MP
Midhun MP

Reputation: 107121

You can use the following code to do this:

#include <stdio.h>

void copyToAnother(FILE *inFile, FILE *outFile)
{
    int ch, flag = 0;
    while(EOF!=(ch=fgetc(inFile)))
   {
        if(ch != '"' && toggle)
        {
          fputc(ch,outFile);
        }
        else
        {
           toggle = toggle ^ 1;
        }
}

int main(void)
{
    FILE *inFile  = fopen("in.txt", "r" );
    FILE *outFile = fopen("out.txt", "w" );

    if (inFile != NULL && outFile != NULL)
    {
        copyToAnother(inFile, outFile);
        fclose(inFile);
        fclose(outFile);
    }
    return 0;
}

Note: In this code. It'll write all the data between all " ".

Upvotes: 1

A4L
A4L

Reputation: 17595

You may want to use fgetc to read one character at a time:

  • Allocate a buffer that is large enough
  • Start reading from the file char by char
  • If you find a " start saving next chars into the buffer
  • Keep saving into the buffer until you reach an other "
  • Terminate you string with a '\0'
  • If you need to remove new lines and have all chars between two " in the same line then just don't save '\r' and '\r' and save a simple space ' ' instead.
  • Repeat until you have consumed the hole file, i.e. fgetc return EOF.

Upvotes: 2

Led
Led

Reputation: 71

You could just use 'strcat' to concatenate your arrays of chars. See that post for a good example : How do I concatenate const/literal strings in C?.

Upvotes: 0

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