Convert String to Integer in C Without Using Atoi Function

Write a Program to Convert String to Integer in C Without Using Atoi Function. C string to an integer. how to convert string to int in c without Atoi. Here we are converting a string to an integer without using an Atoi library function, first, pass the string to a function and then compare it with the first if else condition.

If the condition is true then we can not convert a string into an integer and if the condition is false then we can convert a string to an integer number. Here we took an input number as a string, not as an integer that is why we have to convert the number to an integer or if we input the string then we cannot convert it.

Convert String to Integer in C Without Using Atoi Function

#include <stdio.h>
#include <string.h>

int strToint(char[]);

int main()
{
	/*Convert String to Integer in C Without Using Atoi Function*/

	while (1)
	{
		char str[10];
		int intNum;

		printf("\nEnter Integer Number: ");
		scanf("%s", str);

		intNum = strToint(str);

		if (intNum == 0)
		{
			printf("\nEnter The Number Not String\n\n");
		}
		else
		{
			printf("\nEquivalent Integer Value: %d", intNum);
		}
	}

	return 0;
}

int strToint(char str[])
{
	int i = 0, sum = 0;

	while (str[i] != '\0')
	{
		if (str[i] < 48 || str[i] > 57)
		{
			printf("\nCan't Convert Into Integer");
			return 0;
		}
		else
		{
			sum = sum *10 + (str[i] - 48);
			i++;
		}
	}

	return sum;

}

The Output of Convert String to Integer in C

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