Thread: How To Write an Int to file?

  1. #1
    Registered User
    Join Date
    Aug 2001

    How To Write an Int to file?

    This probably sounds like a dumb question, but I am just trying to write an integer to an output buffer, then write the output buffer to a file:

    /* Declaratives */

    char rptbuf[197];

    input_cnt_msg[] = "Total Input Records Read .......... ";

    int input_rec_cnt = 0;
    int main()
    FILE *reportPtr;
    /* ...... input_rec_cnt is updated in program ..... */
    rptbuf[0] = '\n';
    z = 1;
    for (j=0; j<34; j++, z++) {
    rptbuf[z] = input_cnt_msg[j];}
    rptbuf[z] = input_rec_cnt;
    fputs(rptbuf, reportPtr);

    I know this isn't right. I have tried several ways .... even moving the integer to a string, then moving that one byte at a time to the output buffer. Nothing works.

    Any suggestions? Sorry if this is a stupid question, but I'm new to this language and can't find it in the book.


  2. #2
    Registered User
    Join Date
    Sep 2001
    global variables...

    firstly, it doesnt look like you open the file. You need to use something like:

    reportPtr = fopen("filename", "w");

    this will open a file for writing. (thats what the "w" means).. it will re-write over an existing file if its there.. or it will create a new file.

    input_cnt_msg[] = "Total Input Records Read .......... ";

    ^^there needs to be a char b4 this.

    rptbuf[z] = input_rec_cnt;
    ^^ this is assigning a char and in value..

    if you want to output ints to a file, you could convert them to a string (long way)
    or you can use something like:

    fprintf(reportPtr,"%d\n", intvalue);

    this will output the string to the file pointed to by reportPtr.

    Hope thats helped!

    "THE DAY IS MYNE!!!!
    I'll take famouse titties for $400"
    -Sean Connery, Saturday Night Live

  3. #3
    Guest Sebastiani's Avatar
    Join Date
    Aug 2001
    Waterloo, Texas
    You can't read an integer into a string without converting it first. Play with "itoa()" to make what you wrote work.

    For what your doing, though, why not print the integer directly to file using fprintf(). This also eliminates the need for buffer "rptbuf".

    fprintf(reportPtr, "%s", input_cnt_msg);
    fprintf(reportPtr, "%i", input_rec_cnt);

    And are you opening and closing the file properly?
    #include <cmath>
    #include <complex>
    bool euler_flip(bool value)
        return std::pow
            std::complex<float>(0, 1) 
            * std::complex<float>(std::atan(1.0)
            *(1 << (value + 2)))
        ).real() < 0;

  4. #4
    Registered User
    Join Date
    Aug 2001
    Thank you both for your replies .... I only posted a part of my logic, so as not to confuse the question, but I ended up doing the opposite, because it caused both of you to question what I didn't show in my post.

    I had opened the file, and the input_rec_cnt is just the field name I used, that value is not being entered by the user, so those were not the problem.

    Anyway, I did change the code to not use a buffer space anymore, and I used the fprintf command that both of you recommended, and it works beautifully now!

    Thanks again,

  5. #5
    Join Date
    Aug 2001
    mming, Game DevelopmentCSR >&<>&2Minimization of boolean functions, PROM,PLA design >&0>&WA, USA guitar, dogsCommercial Aviation >&>>&USAProgramming
    I am just trying to write an integer to an output buffer, then write the output buffer to a file
    Just by looking at these words of yours, I'll give you an example of how to do it.
    int main()
    	//integer number
    	int i_number = 20;
    	//output buffer
    	char s_buffer[10];
    	//file pointer initialized to NULL (a special area in memory)
    	FILE *fptr = NULL;
    	//sprintf mean print to a string
    	sprintf(s_buffer, "%d", i_number);
    	//display the string on screen (stdout)
    	//open a file 
    	fptr = fopen("c:\\file","w");
    	//write buffer to file
    	fprintf(fptr,"%s ",s_buffer);
    	return 0;
    Now I'm not saying that this is necessarily the best way to go about writing your program. I don't know what your program should do, but this does what you asked for.
    I compile code with:
    Visual Studio.NET beta2

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