4.1
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0, b = 0;do {printf("请输入一个整数：");scanf("%d", &a);if (a < 0){printf("该整数为负数！\n");}else if (a > 0){printf("该整数为正数！\n");}else{printf("该整数为0\n");}printf("想再来一次吗铁汁？再来--1/不了--2>>");scanf("%d", &b);} while (b == 1);printf("那下次再见啦铁汁！");return 0;}
4.2
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0, b = 0, sum = 0;puts("请输入两个整数");printf("整数a："); scanf("%d", &a);printf("整数b："); scanf("%d", &b);if (a > b)//始终是左大右小{int c = a;a = b;b = c;}do{sum += a;a++;} while (a <= b);printf("大于等于%d小于等于%d的所有整数的和是%d", a, b, sum);return 0;}
4.3
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("请输入一个正整数：");scanf("%d", &a);while (a>=0){printf("%d\n", a);a--;}return 0;}
4.4
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("请输入一个正整数：");scanf("%d", &a);while (a>=1){printf("%d\n", a--);}return 0;}
4.5
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("请输入一个正整数：");scanf("%d", &a);int i = 1;while (i<=a){printf("%d\n", i++);}return 0;}
4.6
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("请输入一个整数：");scanf("%d", &a);if (a % 2 == 0&& a > 2){while (a > 0){printf("%d\n", a -= 2);}}if (a % 2 != 0&& a >0){a = a + 1;while (a > 2){printf("%d\n", a-=2);}}return 0;}
4.7
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>#include<math.h>int main(){int a = 0, i = 1, n = 0;printf("请输入一个整数：");scanf("%d", &a);while (i<a){n = (i *= 2);if(n<a){printf("%d\n", n);}}return 0;}
4.8
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("正整数：");scanf("%d", &a);while (a > 1){printf("*");a--;}return 0;}
4.9
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0, i = 0;printf("正整数：");scanf("%d", &a);while (i < a){if (a % 2 != 0){printf("+");a--;}else{printf("-");a--;}}return 0;}
4.10
#define _CRT_SECURE_NO_WARNINGS#include<stdio.h>int main(){int a = 0;printf("正整数：");scanf("%d", &a);int i = 0;while (i < a){//以下三种输出，自己选一个顺手的~//printf("*\n");//puts("*");putchar('*'); putchar('\n');i++;}return 0;}
