How to store value referenced with pointers in variables?-CodePudding

Actually I have a string looking like this : "1,22,333,,55555,666666,7777777"

From this string I have created two array :

One with the size of each parameter. For the given exemple it looks like this : [1;2;3;0;5;6;7]
The second with the pointer that reference the beginning of each parameter. For the given exemple it looks like this :

    ["1,22,333,,55555,666666,7777777";
    "22,333,,55555,666666,7777777";
    "333,,55555,666666,7777777";
    ",55555,666666,7777777";
    "55555,666666,7777777";
    "666666,7777777";
    "7777777"]

The parameters can change in length and in type but not in order. So i want to store them with typecasting for those concerned

I have tested to sscanf each index of the pointer array but it seems not working

char* format = strcat(strcat("%", params_sizes[0]), "u");
strutest.un = sscanf(params_pointer[0], format);

Do you have any idea that can help me ?

CodePudding user response：

This line

char* format = strcat(strcat("%", params_sizes[0]), "u");

is wrong.

The prototype for strcat is

char *strcat(char *restrict dest, const char *restrict src);

where dest is the destination, i.e. (a pointer to) the object where the concatenated string is stored.

So looking at your code:

strcat("%", params_sizes[0]
       ^^^
       dest !!!

you are trying to store the result in a string literal. That won't work (modifying a string literal in undefined behavior).

You need something like:

char format[1024] = "%";  // Sufficiently big char array that can be modified

strcat(strcat(format, params_sizes[0]), "u");

BTW: Also consider sprintf instead of nested strcat