Question

How to implement a function that converts string to int number in C

Answer 1

#include <stdio.h>

int str2int(const char* s) {

	// go to last digit
	const char* p = s;
	for (; *p >= '0' && *p <= '9'; p++);
	p--;

	// convert to number 
	int intval = 0;
	int  unitposition = 1;
	for (; p >= s; p--) {
		intval += (*p - '0') * unitposition;
		unitposition *= 10;
	}

	return intval;
}

int main()
{
	printf("%d", str2int("9023"));

	return 0;
}


/*

9023

*/

 

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