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bimbam
bimbam
Last Activity: Mar 8 '08, 01:50 PM
Joined: Aug 17 '07
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  • bimbam
    started a topic read float from string and approximation problem
    in C

    read float from string and approximation problem

    Hi,

    I try to read a float in a string using sscanf or atof. It seems to work but then it's a bit strange when I manipulate the value obtained.

    Code:
    float fl;
char  str[]="1.43"

fl=atof(str);

printf("%f\n",floor(1000.0*fl) );
    These lines return : 1429.000000

    It seems to be due to the precision of the float...
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    • bimbam
      replied to using variable names
      in C
      Sorry, that's not what I meant. My question was about the function called "function" in my example that would have as input argument a string and would output the variable of which the name is contained in the string. I realise my explanation is not so clear but it should be easier to understand reading the example at the same time.

      Cheers...
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        Leave a comment:

      • bimbam
        started a topic using variable names
        in C

        using variable names

        Hi,

        Does anyone of you knows how to make a string to be interperted as a variable name in C? For example, is there a function so that the following lines print out "test"?

        Code:
        char variable[10];
strcpy(function("variable"), "test");
printf("%s\n",variable );
        It would simplify a lot of things to me...

        Cheers
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        • bimbam
          started a topic xlib and mouse button
          in C

          xlib and mouse button

          Hi,

          I'm trying to use the Xlib library to detect a mouse button event in C. I'm using linux. I want to run a loop and exit this loop when a mouse button is pressed. It seems possible to me to wait for an event to happen but it it possible to compute something else while we're waiting?

          I thought of something like :

          do {
          ...
          } while !(buttonstate1= =pressed)

          So my question is:...
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          • bimbam
            started a topic loading PNG image in C.
            in C

            loading PNG image in C.

            Hi,

            Could anyone tell me how to load a PNG image into memory?

            Regards
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            • bimbam
              started a topic qsort of an array of pointers to structures
              in C

              qsort of an array of pointers to structures

              Hi,

              I wish to sort an array of pointers to structures. There must be something I don't get.

              Here is my code:
              [CODE=c]
              ...
              typedef struct
              {
              ...
              time_t time;
              }struct_file;

              main()
              {
              struct_file ** tables;
              ...
              qsort( tables,ntables, sizeof(struct_f ile), cmp_struct);
              }

              int cmp_struct( const void...
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              Last edited by bimbam; Sep 29 '07, 10:57 AM. Reason: not finished
              • bimbam
                started a topic passing a (char *) as an argument
                in C

                passing a (char *) as an argument

                Hi,

                I try to write in C a function that can edit a string allocated dynamically. I tried:

                Code:
                int funct(char ** str)
{
int n;
n=strlen("TEST");
(*str)=malloc(sizeof(char)*(n+1));
strcpy(*str,"TEST");
}
                the main is

                Code:
                int main()
{
char * str;
funct(&str);
printf("%s\n",str);
}
                ...
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                • bimbam
                  replied to binary conversion
                  in C
                  OK.

                  So JosAH (or anyone) can you help me?

                  Regards.
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                    Leave a comment:

                  • bimbam
                    replied to binary conversion
                    in C
                    Hi,

                    I tried to compile the examples you sent me. I try to use a Makefile but I'm not too familiar with it. Could you give me a help? Do I need a header file?

                    I called the 2 files you sent me main.c and test.cpp. Here is my makefile:
                    Code:
                    CC=gcc
CPP=g++
CFLAGS=-W -Wall -ansi -pedantic
CXXFLAGS=-W -Wall -ansi -pedantic
LDFLAGS=
EXEC=test

all: $(EXEC)
                    ...
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                      Leave a comment:

                    • bimbam
                      replied to binary conversion
                      in C
                      How do you link the 2 files together?

                      Regards
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                        Leave a comment:

                      • bimbam
                        replied to binary conversion
                        in C
                        Thanks,

                        I'll try that.

                        Regards...
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                          Leave a comment:

                        • bimbam
                          replied to binary conversion
                          in C
                          Thank you for the tip.

                          I don't use C++ but there might be a function in C to do the same?

                          Regards...
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                            Leave a comment:

                          • bimbam
                            started a topic binary conversion
                            in C

                            binary conversion

                            Hi,

                            I wish to compare 2 black and white images of about 4000 pixels. So I have 2 arrays of 4000 integers int of value 0 or 1. My idea was to convert each array to a single binary number built by putting all the integers one after the other. I could then convert this number to a base 10 number. I would use this number as a signature of each image to compare them.

                            The problem is the amount of operations to make to build...
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                            • bimbam
                              replied to dynamic memory allocation of an array of pointers to structures
                              in C
                              Thanks.

                              To 'desallocate', is 'free(p)' enough? Or do I have to do everything in reverse to free each field of all the structures, free the structures abd then free the array?
                              Regards...
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                              • bimbam
                                replied to dynamic memory allocation of an array of pointers to structures
                                in C
                                Thanks a lot for your answer.

                                Everything seems to work. I just want to be sure that I did the memory allocation properly so that nothing will be overwriten later and no memory was wasted.

                                Could you quickly have a look at these few lines to see if everything is "perfect"? Do you have suggestions to improve it?

                                [code=c]
                                #include <stdio.h>
                                #include <stdlib.h>
                                ...
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                                  Leave a comment:

                                • bimbam
                                  replied to dynamic memory allocation of an array of pointers to structures
                                  in C
                                  But in that case, how would you allocate dynamically the memory of an array of pointers if not with 'p=calloc(n,siz eof(struct_p*)) '?

                                  Regards...
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                                    Leave a comment:

                                  • bimbam
                                    replied to dynamic memory allocation of an array of pointers to structures
                                    in C
                                    It works with 'sizeof(struct_ p)' (and '.'). You were right. Thank you for your help.

                                    Regards...
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                                    • bimbam
                                      replied to dynamic memory allocation of an array of pointers to structures
                                      in C
                                      Thank you for your answer.

                                      I used sizeof(struct_p *) and not sizeof(struct_p ). Does'nt it make any difference? I thought that, this way, the elements of the array would be pointers.

                                      Regards...
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                                      • bimbam
                                        started a topic dynamic memory allocation of an array of pointers to structures
                                        in C

                                        dynamic memory allocation of an array of pointers to structures

                                        Hi,

                                        I've been trying to allocate dynamicaly an array of pointers to structures. As it didn't work, I tried to reduce the problem as much as possible. This is what I have :

                                        [code=c]
                                        #include <stdio.h>
                                        #include <stdlib.h>

                                        typedef struct
                                        {
                                        int x;
                                        int y;
                                        }struct_p;


                                        int main()
                                        {
                                        int i,n=2;
                                        struct_p *p;...
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