《C语言入门经典》习题7.1【原创】

《c语言入门经典》习题7.1【原创】

#include 
#include 
#include 

int main(void)
{
	char ch;
	int a = 5;
	long count = 0l,number = 0l;
	char *p = null, *b = null;
	long double sum = 0.0l, result = 0.0l;

	printf("使用说明："
			"\n本程序可对输入的数值进行相加操作。"
			"\n按回车键结束输入。\n"
			"（注意：每次仅限一个数值。）\n\n");

	p = calloc(a, sizeof(char));
	if (p == null)
	{
		printf("\a警告：内存分配失败！\n");
		return 1;
	}

	while (*p != '\n')
	{
		number++;
		printf("请输入第%d个数值：", number);

		count = 0l;
		while (*p != '\n')
		{
			++count;
			ch = getchar();
			if (ch == '\n')
			{
				if (count >= a)
				{
					a += 5;
					b = realloc(p, a*sizeof(char));
					if (b == null)
					{
						printf("\a警告：内存分配失败！\n");
						free(p);
						p = null;
						return 1;
					}
					p = b;
				}
				*(p + count - 1) = ch;
				*(p + count) = '\0';
				break;
			}
			else
			{
				if (count >= a)
				{
					a += 5;
					b = realloc(p, a*sizeof(char));
					if (b == null)
					{
						printf("\a警告：内存分配失败！\n");
						free(p);
						p = null;
						return 1;
					}
					p = b;
				}
				*(p + count - 1) = ch;
				*(p + count) = '\0';
			}
		}
		sum = (long double)atof(p);
		result += sum;
	}
	printf("%lf\n", result);
	free(p);
	p = null;

	system("pause");
	return 0;
}