input_from_txt_file_v1.c

/*

    input_from_txt_file_v1.c

    Task:
    https://web.facebook.com/photo.php?fbid=242589967061798&set=gm.1585074201651424&type=3&eid=ARCIFM0K7WTNghYPEzw9KVJugwAD1egoeIVYeTEbtjmJsRTI4-XDjLkrYOkf7UJOzVb0MnsxGIVSbIWD&ifg=1

    Make txt file with 3 lines each consist of string, long integer and ineger.
    String is terminated by '_' character.
    Read data from such txt file.

    Version with fgets() loads one line at a time and extracts data from such a string.


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/


#include <stdio.h>
#include <string.h>
#include <ctype.h>          // for isdigit()
#include<stdlib.h>          // for exit()

#define LEN 100             // length for strings


// Create the appropriate txt file for input
void make_txt_file_for_input( char FileName[] )
{
    FILE *p_file;           // output txt file

    p_file = fopen(FileName, "w");

    if( p_file == NULL ) {
        printf("\n Error opening output text file ! \n");
        exit(1);
    }

    fprintf( p_file, "Journey To The Centre Of The Earth_   16585426    3 \n" );
    fprintf( p_file, "The C Programming Language_       45213542    4 \n" );
    fprintf( p_file, "Deitel C How To Program 8th Edition_  12685855    5 \n" );

    fclose(p_file);
} // make_txt_file_for_input()


// Read and print data from appropriate txt file
void read_from_text_file( char FileName[] )
{
    FILE *p_file;           // input txt file
    char str_line[LEN];     // string for whole one line of txt file
    char str[LEN];          // for string str
    char str_num1[LEN];     // for string num1
    char str_num2[LEN];     // for string num2
    unsigned num1;          // unsigned number
    int num2;               // integer number
    int i, j;               // loop itterators, indexes for strings

    p_file = fopen(FileName, "r");

    if( p_file == NULL ) {
        printf("\n Error opening input text file ! \n");
        exit(1);
    }

    // fgets() loads one row at a time from the input file and processes it
    while( fgets(str_line, LEN, p_file) != NULL )
    {
        printf("%s\n", str_line);   // loaded the whole line in string str_line

        // read str until character '_' , character '\n' or end of file EOF
        i = 0;                      // reset index for str_line
        while( str_line[i] != '_' && str_line[i] != '\n' && str_line[i] != EOF )
        {
            str[i] = str_line[i];
            i++;
        }
        str[i] = '\0';              // to finish the string str, cutting '_'
        printf("%s\n", str);

        // read num1
        // skip until str_line[i] is not a number, character '\n' or end of file EOF
        while( !isdigit( (int)str_line[i] ) && str_line[i] != '\n' && str_line[i] != EOF )
        {
            i++;
        }

        // read digits of str_num1 while str_line[i] is digit, until character '\n' or end of file EOF
        j = 0;                      // reset index for str_num1
        while( isdigit( (int)str_line[i] ) && str_line[i] != '\n' && str_line[i] != EOF )
        {
            str_num1[j++] = str_line[i++];
        }
        str_num1[j] = '\0';         // to finish the string str_num1
        num1 = atol(str_num1);      // convert string to long
        printf("%u\n", num1);

        // read num2
        // skip until str_line[i] is not a number, character '\n' or end of file EOF
        while( !isdigit( (int)str_line[i] ) && str_line[i] != '\n' && str_line[i] != EOF )
        {
            i++;
        }

        // read digits of str_num2 while str_line[i] is digit, until character '\n' or end of file EOF
        j = 0;                      // reset index for str_num2
        while( isdigit( (int)str_line[i] ) && str_line[i] != '\n' && str_line[i] != EOF )
        {
            str_num2[j++] = str_line[i++];
        }
        str_num2[j] = '\0';         // to finish the string str_num2
        num2 = atoi(str_num2);      // convert string to long
        printf("%d\n\n", num2);
    }

    fclose(p_file);
} // read_from_text_file()


int main(void)
{
    // make txt file with data for latter input from
    make_txt_file_for_input( "txt_file_for_input.txt" );

    // read and print data from text file
    read_from_text_file( "txt_file_for_input.txt" );


    return 0;
}