File Processing

File and Streams
-When a C  program run, there a three standard streams activated :
1.Standard Input Stream
2.Standard Output Stream
3.Standard Error Stream

File Definition:
File is a collection of record.Record is a collection of field.Field is a block of byte.Byte is  collection of bit.


Open File
-Opening a File using fopen():
a. File *fopen ( const char *filename, const char *mode);
b. fopen() defined at <stdio.h>
c. fopen() return a pointer to the start of a buffer area. Null will be returned if file unable to open.

- Possible mode value:
   Mode                 Description
a. "r"                    opening a file to be read.
b. "w"                   creating a file to be written.
c. "a"                     opening a File for data append.

Close File
-Closing a File using fclose():
 a. int fclose (File *stream);

Example writing data to file text.txt using fprintf:
#include <stdio.h>int main(void)
{    FILE *fp;
    fp=fopen("test.txt","w");    if(fp==NULL){        printf("File test.txt can’t be created\n");        exit(1);    }    fprintf(fp,"%d %s %f\n",1,“Amir", 3.95);    fprintf(fp,"%d %s %f\n",2,“Tono", 3.15);    fclose(fp);    return 0;}

Example writing data to file text.txt using fscanf:

#include <stdio.h>

int main(void)

{

  FILE *fp;  int no; char name[20]; float gpa;

  fp=fopen("test.txt","r");

  if(fp==NULL){

  printf("File test.txt can’t be opened\n");   exit(1);

  }

  fscanf(fp,"%d %s %f",&no,name, &gpa);

  printf("%d %s %f\n",no,name,gpa);

  fscanf(fp,"%d %s %f",&no,name, &gpa);

  printf("%d %s %f\n",no,name,gpa);

  fclose(fp);     return 0;

}

Example writing data to file text.txt using fwrite:

#include <stdio.h>

int main(void)

{

    FILE *fp;

    int Arr[]={1,2,3,4,5};

    fp=fopen("test.dat","w");

    if(fp==NULL){

        printf("File test.dat can’t be created\n");

        exit(1);

    }

    fwrite(Arr,sizeof(Arr),1,fp);

    fclose(fp);

    return 0;

}

 

Pointer adalah suatu variable yang menuju ke alamat variable yang lain.

Contoh :

int i, *ptr, **ptr_ptr;

ptr = &i;

ptr_ptr =&ptr

Contoh asli :

*ptr = 5;

*ptr_ptr = 9

Standar Library ( string.h ) :

-strlen()

-strcpy(s1,s2)

-strncpu(s1,s2,n)

-strcat(s1,s2)

-strncat(s1,s2,n)

-strcmp(s1,s2)

A.Perbedaan dari While dan Do-While :

•While : Kita mengecek suatu kondisi baru kita melakukan sesuatu.

•Do While : Kita Melakukan sesuatu terlebih dahulu baru kita cek kondisinya.

Contoh dari Do-While adalah saat kita datang ke Mesin ATM kita pasti memasukan pin kartu atm kita baru mesin mengecek apakah pin kita benar atau salah.

B.While

While(exp)statements

Atau jika memiliki banyak statements dapat ditulis seperti ini

While(exp){

Statements1

Statements2

...

}

C.Do-While

do{ 

<statements>;

}while(exp):

Di While / Do-While ini , program akan terus me looping jika kondisinya masih terpenuhi atau benar.

D.For

for(exp1;exp2;exp3)

Atau jika banyak

for(exp1;exp2;exp3)

      for(exp1;exp2;exp3)

exp1 = untuk inisiliasasi.

exp2 = untuk memasukan kondisinya.

exp3 = untuk increament/dicreasement.