CODEWITHSUNDEEP
carraysstring
bslqy
bslqy

Reputation: 233

How to store fixed length string in c

I would like to read some fixed length string in a text file and store them in an array. The way I read the strings is by fscanf(fp,"%c",&char[]);

However, as the data are seperated by white space, I would like the array index to indicate each string instead of each character.

How would I do that? Should I use fgets() with certain length instead of fgetc()? Thanks

#include <stdlib.h>
#include <stdio.h>
#define MAX 1000000  //one row of double = sizeof(Double) *4400
#define keyLength  15


void readKey(char* fileName)
{
    FILE *fp;
    int i, j;
    char  ch;


    if ((fp = fopen(fileName, "r")) == NULL) {
    printf("can not open this file!\n");
    exit(1);
    }

  int row = 0;
  while ((ch = fgetc(fp)) != EOF)
  {
    if (ch == '\n')
    row++;
  }   //Count the line

  rewind(fp); //Going back to the head of the matrix

  int col = 0;
  while ((ch = fgetc(fp)) != '\n') //(ch=fgetc(fp))!='\n'&&(ch=fgetc(fp))!='\r'
  {
    if (ch == ' ')
        col++;
  }
  col++; //Count the col

  char** jz = malloc(row * sizeof(char*)); //Allocate spaces
  for (i = 0; i < row; i++)
    jz[i] = malloc(col * keyLength*sizeof(char));

  rewind(fp);

  for (i = 0; i < row; i++) //Read in the data
    for (j = 0; j < col * keyLength; j++) {
      if (!fscanf(fp, "%c", &jz[i][j])) {
        break;
      }
    }

//Print the matrix
  for (i = 0; i < row; i++)
    for (j = 0; j < col * keyLength; j++) {
      printf("%c", jz[i][j]);
      if (j + 1 == col) printf("\n");
    }
  fclose(fp);

  printf("%d row, %d  col ",row,col);

}



 int main(void) {

readKey("keys.txt");

}

I print the matrix to check if the scanning is successful. enter image description here enter image description here

Upvotes: 2

Views: 440

Answers (2)

BLUEPIXY
BLUEPIXY

Reputation: 40145

When row and col are determined
allocate by following way:

char (*jz)[col][keyLength] = malloc(row * col * keyLength);//meant char jz[row][col][keyLength]

Read from a file: 

for(i = 0; i < row; ++i){
    for(j = 0; j < col; ++j){
        fscanf(fp, "%s", jz[i][j]);
    }
}

Print the matrix:

for(i = 0; i < row; ++i){
    for(j = 0; j < col; ++j){
        if(j)
            putchar(' ');
        printf("%s", jz[i][j]);
    }
    putchar('\n');
}

Upvotes: 0

sav_a
sav_a

Reputation: 121

simple example of reading from file with fgets() 

#include <stdio.h>
#include <stdlib.h>

#define LINE_LENGTH 6

int main(int argc, char** argv)
{
  int i = 0;
  FILE *file_ptr;
  char *string=(char*)calloc(LINE_LENGTH,sizeof(char));

  file_ptr = fopen("file.txt", "r");

  while(1)
    {
      if(fgets(string, LINE_LENGTH, file_ptr) == NULL)
         break;
      fgetc(file_ptr);
      printf("\nline[%d] = %s\n", i+1, string);
      i++;
    }

  fclose(file_ptr);

  return 0;
}

file.txt

12344 45678 99870 33389 11234

Upvotes: 1

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