c语言-将字符串转换成整数（类似atoi()函数）

//模拟实现atoi()函数
//把字符串变成整数

#define _CRT_SECURE_NO_WARNINGS 1
#include 
#include   //isdigit()函数的库函数

int MyAtoi(char* pa)
{
	int flat = 1, sum = 0;

	if (*pa == '+')
	{
		if (isdigit(*(++pa)));
		else
			return 0;
	}
	else if (*pa == '-')
	{
		if (isdigit(*(++pa)))
		{
			flat = -1;
		}
		else
			return 0;
	}
	else if (isdigit(*pa));
	else
	{
		return 0;
	}

	while (isdigit(*pa))
	{
		sum = sum * 10 + (*pa - '0');
		pa++;
	}
	return sum * flat;
}

int main()
{
	char arr1[] = "12434";
	char arr2[] = "+3523";
	char arr3[] = "-34523";
	char arr4[] = "ab2354";
	char arr5[] = "23a355b9";
	char arr6[] = "+a28";

	int m = MyAtoi(arr1);
	printf("%d\n", m);
	m = MyAtoi(arr2);
	printf("%d\n", m);
	m = MyAtoi(arr3);
	printf("%d\n", m);
	m = MyAtoi(arr4);
	printf("%d\n", m);
	m = MyAtoi(arr5);
	printf("%d\n", m);
	m = MyAtoi(arr6);
	printf("%d\n", m);

	return 0;
}
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