extract numbers from char array into array of pointers

**lmanukyan** · 10-05-2016

i need to extract numbers from user input. i think it's best to extract them into array of pointers because in that case i can refer to the numbers with their index.

i can't assign an int (which i extracted from a char array) to char* a[];

how should i do that?

the code i've written so far, this is just a piece of the actual code:

Code:

#include <stdio.h>
#define SIZE 100

int getCurrentNumber(int i) {
  . . .
  return res;
}
int main() {


  std::cout << "Enter expression: ";
  fgets(expr, SIZE, stdin);


  char* simplified[SIZE];
  int i=0;
  int j = 0;


  simplified[j++] = getCurrentNumber(i);

  return 0;
}

**Salem** · 10-05-2016

Why not extract them to an array of int's then?

Presumably, you want int's at some point.

**lmanukyan** · 10-05-2016

well, the user input is a math expression, so i wanna separate the numbers and the operations, like this:

Code:

char* a[] = {"566", "+", ...}

**Salem** · 10-05-2016

So getCurrentNumber() is actually mis-named and you perhaps want to get the next token?

A token being either the string representation of a number, such as "123" or an operator such as "+"

If everything is space separated, you might look at strtok(), but read all the warning labels before proceeding.

**lmanukyan** · 10-05-2016

With strtok I guess I could assign char*'s to array of ptrs, but I should define a whole list of delimiters so its not convenient. And no, everything is not space separated.

**Xupicor** · 10-05-2016

You might be better off writing a parser/tokenizer yourself then. Your input data will be a c-string, and your output data will be a series of tokens you can work with.
Since, presumably, you want to evaluate that math expression at some point, you may want to write another procedure that will take a series of tokens and using some predefined rules (operator precedence, unary/binary nature of operators, brackets, etc) make that into, say, abstract syntax tree, which may be used as input data in yet another procedure that will go through and evaluate it.

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