第4章 程序段的反复执行4.2while语句P128练习题（题及答案）

（（1）阅读程序

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main(){int n,s=0;cin >> n;while(n){s = s * 10 + n % 10;n /= 10;}cout << s << endl;return 0;
}

分别输入：0 1024 1234567890

输出结果：0 4201 987654321

（（2）阅读程序

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main(){int n;cin >> n;while(n != 0){cout << n % 2;n /= 2;}return 0;
}

输输入： 4 0

输输出：001 无输出

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main(){int n,sum = 0;cin >> n;while(n){sum += n % 10;n /= 10;} cout << sum << endl;return 0;
}

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main() {int n, m, i, j;cin >> n >> m;i = n;j = m;while(i != j) {if(i > j)i -= j;elsej -= i;}if(i == 1)cout << "Yes";elsecout << "No";return 0;
}

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main(){int l,r,ans = 0;cin >> l >> r;for(int i = l;i <= r; i++){//拆位int x = i;while(x){int c = x % 10;if(c == 2) ans++;x /= 10;} }cout << ans << endl;return 0;
}

#include <bits/stdc++.h>
using namespace std;
//汤永红
int main() {int n, K;double Sn, An;printf("Please input K(1<=K<=15):");scanf("%d", &K);if ((K >= 1) && (K <= 15)) {n = 1;while(1) {An = 1.0 / n;Sn += An;if (Sn > K) {break;}n++;}printf("n=%d,Sn=%f\n", n, Sn);} else {printf("Input error!Please input again!\n");}return 0;
}

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#include <bits/stdc++.h>
using namespace std;
//汤永红
char c;
int main() {while((c = getchar() ) != '\n') {if(islower(c)) {putchar('a' + (c - 'a' + 3) % 26);} else if(isupper(c)) {putchar('A' + (c - 'A' + 3) % 26);} else {putchar(c);}}return 0;
}