Read from a text file..

This is a discussion on Read from a text file.. within the C Programming forums, part of the General Programming Boards category; Compiler - Turbo c++ v4.5 (Borland) OS - Win Me/98 Well i have created a program to write to a.txt ...

  1. #1
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    Question Read from a text file..

    Compiler - Turbo c++ v4.5 (Borland)
    OS - Win Me/98
    Well i have created a program to write to a.txt file
    here's the part of the codes:

    Code:
    add()
    {
    	int x;
    	ptr=fopen("data.txt","a+");
    	for(x=0;x<2;x++)
    	{
    		printf("\nID: ");
    		scanf("%d",&field[x].id);
    		printf("\nName: ");
    		scanf(" %[^\n]",field[x].name);
    		printf("\nQty: ") ;
    		scanf("%d",&field[x].qty);
    		printf("\nPrice: ") ;
    		scanf(" %lf",&field[x].price);
    
    		fprintf(ptr, "%d|", field[x].id);
    		fprintf(ptr, "%s|", field[x].name);
    		fprintf(ptr, "%d|", field[x].qty);
    		fprintf(ptr, "%.2lf\n", field[x].price);
    	}
    	fclose(ptr);
    	return 0;
    }
    File contents stored like below
    ID|toyname|qty|price

    Ex.:
    001|mickey mouse|12|25.00
    002|donald duck|21|23.10
    003|abc,..|17|5.00

    1) How do i read line by line and display it on the screen without the "|"?
    Ex. ID : 001
    Toy: mickey mouse
    Qty: 12
    Price : 25.00

    ID : 002
    Toy: donald duck
    Qty: 21
    Price : 23.10

    Please provide me a simple program code which can read the data..

  2. #2
    ATH0 quzah's Avatar
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    14,826
    Use fscanf.

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
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    The fscanf will not work correctly on the "mickey mouse" field. It will copy "mickey" into the variable (it stops copying when it reaches a white space character).

    Long winded, but try this.


    #include "stdio.h"
    #include "stdlib.h"
    #include "string.h"

    static void ParseFunction(char *FileBuf, int *int1, char *str1, int *int2, float *float1);
    static void CopyStrField(char *FileBuf, char *str1, int *x);
    static void CopyIntField(char *FileBuf, int *int1, int *x);
    static void CopyFloatField(char *FileBuf, float *float1, int *x);

    #define PARSE_CHAR '|'

    int main(int argc, char* argv[])
    {
    char FileBuf[31];
    int int1;
    int int2;
    char str1[31];
    float float1;

    /* fill FileBuf with some test data */
    strcpy(FileBuf, "001|mickey mouse|12|25.00");

    /* this function will parse the individual fields */
    ParseFunction(FileBuf, &int1, str1, &int2, &float1);

    /* display the results */
    printf("int1: (%03d)\n", int1);
    printf("str1: (%s)\n", str1);
    printf("int2: (%d)\n", int2);
    printf("float1: (%1.2f)\n", float1);

    return 0;
    }

    static void
    ParseFunction(char *FileBuf, int *int1, char *str1, int *int2, float *float1)
    {
    /* if you need to parse more fields, change this value
    pass more variables in */
    #define FIELD_COUNT 4
    //sscanf(FileBuf, "%d|%s|%d|%f", int1, str1, int2, float1);
    int i;
    int x = 0;

    for (i = 1 ; i <= FIELD_COUNT ; i++)
    {
    switch (i)
    {
    case 1:
    CopyIntField(FileBuf, int1, &x);
    break;

    case 2:
    CopyStrField(FileBuf, str1, &x);
    break;

    case 3:
    CopyIntField(FileBuf, int2, &x);
    break;

    case 4:
    CopyFloatField(FileBuf, float1, &x);
    break;

    default:
    printf("Invalid field number\n");
    break;
    }
    }
    }

    static void
    CopyStrField(char *FileBuf, char *str1, int *x)
    {
    int i = 0;

    while (FileBuf[*x] != '\0' && FileBuf[*x] != PARSE_CHAR)
    {
    str1[i] = FileBuf[*x];
    (*x)++;
    i++;
    }
    (*x)++;

    str1[i] = '\0';
    }

    static void
    CopyIntField(char *FileBuf, int *int1, int *x)
    {
    int i = 0;
    char TmpStr[10];

    while (FileBuf[*x] != '\0' && FileBuf[*x] != PARSE_CHAR)
    {
    TmpStr[i] = FileBuf[*x];
    (*x)++;
    i++;
    }
    TmpStr[i] = '\0';

    (*x)++;

    *int1 = atoi(TmpStr);
    }

    static void
    CopyFloatField(char *FileBuf, float *float1, int *x)
    {
    int i = 0;
    char TmpStr[10];

    while (FileBuf[*x] != '\0' && FileBuf[*x] != PARSE_CHAR)
    {
    TmpStr[i] = FileBuf[*x];
    (*x)++;
    i++;
    }
    TmpStr[i] = '\0';

    (*x)++;

    *float1 = atof(TmpStr);
    }

  4. #4
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    Location
    Australia
    Posts
    212
    I recommend have your data in the text file like

    001
    Mickey Mouse
    12
    25
    002
    etc...

    then you can use to read the data like this

    Code:
    fscanf(fptr,"%d\n",&item);
    fgets(product, 150, fptr);  //Gets on or more words depending on characters
    fscanf("%d\n %f\n",&qty, &price);
    Or something similar

  5. #5
    ATH0 quzah's Avatar
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    The fscanf will not work correctly on the "mickey mouse" field. It will copy "mickey" into the variable (it stops copying when it reaches a white space character).
    Yes it will. You just have to know how to use it.

    fscanf( fp, "%[^|]", mybuffer );

    Quzah.
    Hope is the first step on the road to disappointment.

  6. #6
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    thanks! for the code anonymous!

    kwigibo: i also want to use that way but the instruction given is like that..

    btw quzah if i use fscanf .. what while condition should i use?

    how to make it read line by line till the end of file?
    could u provide a sample code...

  7. #7
    ATH0 quzah's Avatar
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    14,826
    Line by line? fgets will read whole lines.

    For a record like this:

    001|mickey mouse|12|25.00

    fscanf( fp, "%d|%[^|]%d|%f", &number, buffer, &number2, &floatynumber );

    I believe that's correct.

    Quzah.
    Hope is the first step on the road to disappointment.

  8. #8
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    1) quzah it seems that it does't work after the name

    Code:
    	struct details temp;
    	fscanf( ptr, "%d|%[^|]%d|%f", &temp.id, temp.name, &temp.qty,
    		&temp.price);
    	printf("%d\n", temp.id);
    	printf("%s\n", temp.name);
    	printf("%d\n", temp.qty);
    	printf("%.2f\n", temp.price);
    it prints out the id and the name correctly but the rest not..

    this is the content inside txt
    1|1 tg|1|1.00

    result:
    1
    1 tg
    8823
    0.00


    2) is this while loop works? If i wanto read all the contents of txt n print it all out on screen
    Code:
    while (!feof(ptr))
    {
        fscanf(......
        printf("%d", temp.id);
    };

  9. #9
    ATH0 quzah's Avatar
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    Replace this:

    fscanf( fp, "%d|%[^|]%d|%f", &number, buffer, &number2, &floatynumber );

    With this:

    fscanf( fp, "%d|%[^|]|%d|%f", &number, buffer, &number2, &floatynumber );

    Works like a champ.

    Quzah.
    Hope is the first step on the road to disappointment.

  10. #10
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    yes! it works greaT!

    thanks quzah!

  11. #11
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    Guest
    Hi! again!


    Code:
    add()
    {
    	int x;
    	ptr=fopen("data.txt","a+");
    	for(x=0;x<2;x++)
    	{
    		printf("\nID: ");
    		scanf("%d",&field[x].id);
    		printf("\nName: ");
                                    //Here's the code changed..
                                    fgets(field[x].name, 25,stdin );
                                    fflush(stdin);
                           //      scanf(" %[^\n]",field[x].name);
    		printf("\nQty: ") ;
    		scanf("%d",&field[x].qty);
    		printf("\nPrice: ") ;
    		scanf(" %lf",&field[x].price);
    
    		fprintf(ptr, "%d|", field[x].id);
    		fprintf(ptr, "%s|", field[x].name);
    		fprintf(ptr, "%d|", field[x].qty);
    		fprintf(ptr, "%.2lf\n", field[x].price);
    	}
    	fclose(ptr);
    	return 0;
    }
    I just changed my code for the Name Input.. i want it to only accept 25 chars only.

    the prob is when it stored into text file :

    ex:

    1|mickey
    mouse|12|25.00
    2|donald
    duck|21|23.10

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