7 replies to this topic

[ThemePark]

I'm in the midst of making a C version of a Java program I have developed, and in the same time learning C. I have run into two problems, and while I understand why they are problems, I don't know the solutions.

1. I have an array which I need to move back and forwards in, so I've made a pointer to the array. In Java, I use an iterator and it's next and previous methods to check if I have reach the end of the arraylist. I'm thinking of using sizeof to check if I'm still within the array, but my question is if sizeof(array[0]) would give the same result as sizeof(array[1]). I'm aware of the solution to put a \0 at the end of the array to signify that I have reached the end, and that will be the solution if this doesn't work.

2. I have two functions which have the same name and the same return type, but one has one parameter and calls the other function using a variable specified in the file, and that other function has two parameters. I'm aware of the possibility to use variable parameters in C, but since I only want to have exactly one or two parameters, I would like to avoid this approach.

[Flying Dutchman]

1. sizeof operator returnes size of data type in bytes.

int a;
printf("%d", sizeof(a));   // on 32-bit systems is 4

Best solution I can think of, have a "global" index counter, by global I mean pass it to those 2 functions and check wheter it's out of range.

2. C does not support function overloading while C++ does. You will have to rename one function.

[Ancient Dragon]

sizeof(array[0]) will return the same thing as sizeof(array[1]). Neither will return the value you are looking for if array is a pointer, and neither will return the size of an array.

[ThemePark]

Thanks, I have now changed the name of the function, and I'm using \0 at both ends of the array to know when the array starts and stops. I have however come across one more problem.

I need to concatenate a string for a file name for fopen. In Java I could just + to concatenate strings with variables. I know of strcat, but that takes char, and I have a mixture of strings and unsigned chars. So how can I make this work?

[Flying Dutchman]

By strings you mean arrays of chars? And why do you need unsigned chars? All numbers and English letters have values less than 128(decimal).

[ThemePark]

I mean like this:

"Some string" + number + "some other string"

where number is an unsigned char.

[mnirahd]

Hi,

You can use strncat to concatenate two string to make them one

for example

char *str ="C:\\folder1";

char *str2 = "\\text.txt";


strncat(str, str2, strlen(str2));

//the result would be str = c:\folder1\text.txt

I hope this helps!

Munir

[Ancient Dragon]

use sprintf() to do all the hard work

char* s1 = "something";

char* s2 = "something else";

int number = 123;

char result[255] = {0};

sprintf(result,"%s%d%s", s1,number,s2);

In c++ programs you can to that with stringstream class instead of sprintf().