Thread: atoi and const char not being very friendly

isbn.cpp: In function 'int isValid(const char*)':
isbn.cpp:25: error: invalid conversion from 'const char' to 'const char*'
isbn.cpp:25: error: initializing argument 1 of 'int atoi(const char*)'
isbn.cpp:25: error: ISO C++ forbids comparison between pointer and integer
isbn.cpp:25: error: ISO C++ forbids comparison between pointer and integer

Code:

Function
int isValid(const char str[])

Code:

Line giving errors
/* determine if string contains non-numeric 
		characters (aside from check digit being an 'X') */
		for (int i = 0; i < 10; i++)
			/* fail check if atoi returns fail to convert (0),
			character being checked is not 0 and last digit is 
			not an "X" */
			if (atoi(str[i]) == 0 and str[i] != "0" and (i != 9 and str[i] != "X"))
				validNumerals = false;

Now, these errors go away if I put const char* str[] rather than const char str[] but then strlen does not work.

Any advice?

Code:

if (atoi(str[i]) == 0 and str[i] != "0" and (i != 9 and str[i] != "X"))

This line contains several errors:

First atoi() converts a C-string (a NULL terminated character string) to an integer. You are not supplying a C-String, you are supplying an character.

Second C has no operator named "and" you would need "&&".

Third you can not compare a character to a character string

Code:

str[i] != "X"

You would need to replace the quotation marks with the single quote 'X'.

Jim

This is a C++ forum though ..... "and" is a reserved keyword in C++ and specified as an alternative representation of &&.

I stand corrected. That's good to know.



Jim

rewind is in <cstdio>, although you're not supposed to use it with an <iostream> stream (use seekg instead)