to complete a Tab ?

[juls]

hello,

i would like to complete a char* tab
you can see the code i want :

int deb=0,fin=48i;
char *tab1[50];
char T[50];

for(i=deb;i<=fin;i++)
{
sprintf(T,"%d",i);
tab1[i]=T;
}

my problem : tab1[i] is always the same value
i need to have tab1[0]="0" and tab[1] = "1" etc, but i have tab1[0]=tab[1]=...=tab[fin] : i think it's due to the adress !!

I don't want to use 'string' because i have a function which works with char !!!

So, please what should i do ?

[LB]

juls wrote:

I don't want to use 'string' because i have a function which works with char !!!

std::string has a member function .c_str() which gives you what you want.

std::vector<std::string> nums;
for(std::size_t i = 0; i < 50; ++i)
{
    nums.push_back(std::to_string(i));
}

Don't be afraid to use the C++ Standard Library as it is meant to be used.

[juls]

in fact i have ever used .c_str() but the problem is the same : when i want to convert string to *char i have the last character (here it's "50" ) in every cases of my *char : tab1[0]="50", tab1[2]="50", etc... but i need to put 0,1, ... 50 in tab1

[LB]

It works fine for me: https://ideone.com/BSxW77
Make sure you #include <vector>

juls wrote:

when i want to convert string to *char i have the last character (here it's "50" ) in every cases of my *char!

I do not understand what you mean.

[juls]

i want to read : tab[0]=0 and tab[1]=1 etc
but the code you shew does :
tab[0]=tab[1]=.......= tab[50]=50

if a follow you, i have a string, but i use a function which does :
Myfunction(char a, char b)

so i have to convert string to char, and the problem continues : tab[0]=tab[1] =....=50 : it's not what i'm waiting for !

[LB]

juls wrote:

but the code you shew does :
tab[0]=tab[1]=.......= tab[50]=50

No, the code I showed clearly does not do anything like that at all. You can even see the output below the code: https://ideone.com/BSxW77

juls wrote:

if a follow you, i have a string, but i use a function which does :
Myfunction(char a, char b)

A char can only contain one digit, so you can't store "10" or higher in a char.

[juls]

A char can only contain one digit, so you can't store "10" or higher in a char.

yes but it's not a problem if a put for example :
tab1[0]="1565255";
tab1[1]="55447";
Myfunction (tab1[0],tab1[1]) .. it works in Myfunction !!!

so my problem is just how to fill tab1[i] for i from 0 to 50 even if a use a string ???

and that is curiously NOT OK :
for(i=deb;i<=fin;i++)
{
sprintf(T,"%d",i);
tab1[i]=T;
}

[LB]

These three functions are extremely different:

Myfunction(char a, char b)

Myfunction(char *a, char *b)

Myfunction(char const *a, char const *b)

Which one are you using? It should be the third one.

[juls]

please, don't worry about it !! i just need to fill tab1

i want
tab1[0]="0"
tab1[1]="1"
...
...
tab1[50]="50"

but unfortunately i have
tab1[0]="50"
tab1[1]="50"
....etc
when i ask it to show me that using that code :
for(i=0;i<=50;i++)
{
sprintf(T,"%d",i);
tab1[i]=T;
}

[LB]

The issue is that you copy the pointer instead of the string, so every element of the array points to the same string. This is why you should use std::string to avoid such issues.

[juls]

ok it's surely true, but i don't see how to fill tab1 after that ?

[LB]

If you insist on not using std::string, your only option is to allocate memory for each element of your array and use strcpy to copy from T into the element. This is messy and requires you to manually clean up the memory afterward.

[juls]

you're right, it works correctly with string.
But it means i have to restart Myfunction (char a[], char b[]), except if it was possible to translate the data 'string' to char !??!

[LB]

http://www.cplusplus.com/reference/string/string/c_str/
http://en.cppreference.com/w/cpp/string/basic_string/c_str

[juls]

Thank you LB for your answer !

I have a new request :
now, i would like to do stcmp(string,string)
it works only as well as strcmp(char*,char*)

so what can i do please ?

[LB]

Use the == operator when using std::string, no need to call any extra function.

[juls]

ok thank you, in fact it was so easy !!