提高篇第20-21課第四題

#include <stdio.h>
#include <stdlib.h>
//第四題，冒泡排序法
int main()
{
	double salary[500];
	double temp_num;
	int i,j;
	FILE *fp1,*fp2;
	fp1 = fopen("salary.txt", "r");
	fp2 = fopen("ordered_salary.txt", "w");
	for (i = 0; i < 500; i++)
	{
		fscanf(fp1, "%lf",&temp_num);
		salary[i] = temp_num*1.2;
	}
	for (i = 0; i < 499; i++)
		for (j = 0; j < 499 - i; j++)
		{
			if (salary[j]>salary[j + 1])
			{
				temp_num = salary[j];
				salary[j] = salary[j + 1];
				salary[j + 1] = temp_num;
			}
		}
	for (i = 0; i < 500; i++)
		fprintf(fp2, "%.2lf\n", salary[i]);
	fclose(fp1);
	fclose(fp2);
	return 0;
}

改進了文件的操作，增加了異常判斷

#include <stdio.h>
#include <stdlib.h>
//第四題，冒泡排序法
int main()
{
	double salary[500];
	double temp_num;
	int i,j;
	FILE *fp1,*fp2;
	fp1 = fopen("salary.txt", "r");
	fp2 = fopen("ordered_salary.txt", "w");
	if (fp1 == NULL)
	{
		printf("打開文件失敗\n");
		exit(1);//exit(1)表示異常退出，exit(0)爲正常退出
	}
	if (fp2 == NULL)
	{
		printf("寫入文件失敗\n");
		exit(1);
	}
	for (i = 0; i < 500; i++)
	{
		if ((fscanf(fp1, "%lf", &temp_num)) != EOF)//判斷讀取到邊界，文件中數據不足500的情況
			salary[i] = temp_num*1.2;
		else
			break;
	}
	for (i = 0; i < 499; i++)
		for (j = 0; j < 499 - i; j++)
		{
			if (salary[j]>salary[j + 1])
			{
				temp_num = salary[j];
				salary[j] = salary[j + 1];
				salary[j + 1] = temp_num;
			}
		}
	for (i = 0; i < 500; i++)
		fprintf(fp2, "%.2lf\n", salary[i]);
	fclose(fp1);
	fclose(fp2);
	return 0;
}