how to convert character to integer c++ (urgent )

[sarada purkait]

hiii
i am taking input from a file as a character and have to convert it into integer to do some operations
eg the character input may be 1 , 0 , 2 etc.
and i need to convert them into integers ..
i have tried doing
unsigned char var_name;
int i;
i=int( var_name);

but it gives wrong output .. probably it is converting the character into ascii..
i cannot understand how to go about it ..
please help ...

[Meetee]

hiii
i am taking input from a file as a character and have to convert it into integer to do some operations
eg the character input may be 1 , 0 , 2 etc.
and i need to convert them into integers ..
i have tried doing
unsigned char var_name;
int i;
i=int( var_name);

but it gives wrong output .. probably it is converting the character into ascii..
i cannot understand how to go about it ..
please help ...

Use atoi function to convert char to int

Cheers!

[sarada purkait]

Use atoi function to convert char to int

Cheers!

hii
thankyou!!
it works ..
by the way .. why cant it convert unsigned char* to const char * ... imean it works when i declare the variable character .. but does not in case i declare the variable unsigned char .. :)

[Meetee]

hii
thankyou!!
it works ..
by the way .. why cant it convert unsigned char* to const char * ... imean it works when i declare the variable character .. but does not in case i declare the variable unsigned char .. :)

For that try this:

unsigned char tmp = 'a';
int num = static_cast<int>(tmp);

For the sake of knowledge:
The static_cast operator converts expression to the type of type-id based solely on the types present in the expression. No run-time type check is made to ensure the safety of the conversion.( from http://msdn2.microsoft.com/en-us/library/ms861534.aspx)

Regards

[weaknessforcats]

You don't need atoi. That's a relic C function.

You convert a char to an int by assigning the char to the int.

char c = 'A';
int x;
x = c;    //x contains 65 which is the ASCII value of 'A'
c = '2';
x = c;    //x contains 62 which is the ASCII value of '2'
x = c - 48;  //x contains 2  
 

A char is just an 8-but integer so you can freely use as an integer.