C語言練習題：迴圈的魅力(C language exercise: Loop’s charisma)
練習一：奇數數列
使用迴圈輸出 1 到 100 之間的奇數。
Exercise 1: Odd Sequence
Print the odd numbers between 1 to 100.
練習一參考解法：
Exercise 1 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int i;
// FOR loop 1
for(i = 1; i <= 100; i += 2)
printf("%d, ", i); printf("\n\n"); // FOR loop 2
for(i = 1; i <= 100; i++)
if(i % 2)
printf("%d, ", i); printf("\n\n"); // WHILE loop
i = 1;
while( i <= 100)
{
if(i % 2)
printf("%d, ", i); i++;
} printf("\n\n"); // DO-WHILE loop
i = 1;
do
{
if(i % 2)
printf("%d, ", i);
i++;
} while(i <= 100); return 0;
}
練習二：範圍
輸出 300 到 500 之間可以被 3 與 11 整除的整數。
Exercise 2: Range
Print the numbers between 300 to 500 which are divisible by 3 and 11.
練習二參考解法：
Exercise 2 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int i;
// FOR loop
for(i = 300; i <= 500; i++)
if(i % 3 == 0 && i % 11 == 0)
printf("%d, ", i); printf("\n\n"); // WHILE loop
i = 300;
while( i <= 500)
{
if(i % 3 == 0 && i % 11 == 0)
printf("%d, ", i); i++;
} printf("\n\n"); // DO-WHILE loop
i = 300;
do
{
if(i % 3 == 0 && i % 11 == 0)
printf("%d, ", i);
i++;
} while(i <= 500); return 0;
}
練習三：星星三角形
設計一程式，輸出底下的星星三角形。
Exercise 3: Star Triangle
Design a C program that print the star triangle.
練習三參考解法：
Exercise 3 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int i, j; for(i = 0; i <= 4; i++)
{
for(j = 0; j <= i; j++)
{
printf("*");
}
printf("\n");
}
return 0;
}
練習四：乘法表
輸入一個整數，程式輸出此整數從 1 乘到 10 的結果，例如輸入整數 7 時，輸出結果會是
7 * 1 = 7
7 * 2 = 14
7 * 3 = 21
.
.
.
7 * 10 = 17
Exercise 4: Multiplication table
Read an integer from user and print it’s multiplication table up to 10. For example, if user give 7, the output will be look like the following:
7 * 1 = 7
7 * 2 = 14
7 * 3 = 21
.
.
.
7 * 10 = 17
練習四參考解法：
Exercise 4 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int num;
printf("Enter an integer:");
scanf("%d", &num); for(int i = 1; i <= 10; i++)
printf("%d * %d = %d\n", num, i, (num*i)); return 0;
}
練習五：等差數列加總
設計一程式可算出底下等差數列的總和。
1 + 4 + 7 + 10 + 13 + … + 97 + 100
Exercise 5: Sum of an Arithmetic Series
Write a C program to print the summation of the following series:
1 + 4 + 7 + 10 + 13 + … + 97 + 100
練習五參考解法：
Exercise 5 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int n, sum = 0;
for(n = 1; n <= 100; n += 3)
sum = sum + n; printf("Sum is %d\n", sum);
return 0;
}
練習六：等比數列加總
設計一程式可算出底下等比數列的總和。
1 + 2 + 4 + 8 + 16 + … + 524288 + 1048576
Exercise 6: Sum of a Geometric Series
Write a C program to print the summation of the following series:
1 + 2 + 4 + 8 + 16 + … + 524288 + 1048576
練習六參考解法：
Exercise 6 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
long n, sum = 0;
for(n = 1; n <= 1048576; n *= 2)
sum = sum + n; printf("Sum is %ld\n", sum); return 0;
}
練習七：星星三角形二
設計一程式，輸出底下的圖形。
Exercise 7: Star Triangle 2
Design a C program that print the following star triangle.
練習七參考解法：
Exercise 7 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int i, j; for(i = 0; i <= 4; i++)
{
for(j = 4; j >= i; j--)
{
printf("*");
}
printf("\n");
}
return 0;
}
練習八：英文字母
使用迴圈來輸出英文的大小寫字母。
Exercise 8: Alphabets
Write a C program that uses loop to display English alphabet.
練習八參考解法：
Exercise 8 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
char letter; printf("Small letters: ");
for(letter = 'a'; letter <= 'z'; letter++)
printf("%c ", letter); printf("\n\n");
printf("Large letters: ");
for(letter = 'A'; letter <= 'Z'; letter++)
printf("%c ", letter); return 0;
}
練習九：迴圈與條件判斷
設計一個程式可不斷讓使用者輸入一個整數，直到輸入 0 才結束程式。並判斷此整數是奇數或是偶數。
Exercise 9: Loop and conditions
Design a C program to determine whether an integer is odd or even repeatedly until 0 is entered.
練習九參考解法：
Exercise 9 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int number; do
{
printf("Please input an integer:");
scanf("%d", &number); if( number % 2 )
printf("%d is odd.\n", number);
else
printf("%d is even.\n", number);
}while(number != 0); return 0;
}
練習十：費氏數列
設計可以輸入一個整數 N ，輸出到整數 N 的費氏數列。例如當 N = 22 時，程式輸出：0, 1, 1, 2, 3, 5, 8, 13, 21,
Exercise 10: Fibonacci sequence
Write a C program that gets an integer from user and display Fibonacci numbers up to N. If N is 22, the program should print: 0, 1, 1, 2, 3, 5, 8, 13, 21,
練習十參考解法：
Exercise 10 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int n;
printf("Please enter an integer:");
scanf("%d", &n); int first = 0, second = 1, tmp; while(first <= n)
{
printf("%d, ", first);
tmp = first + second;
first = second;
second = tmp;
} return 0;
}
練習十一：數字圖案
設計一程式輸出下圖上的數字圖案。
Exercise 11: Number Pattern
Design a C program to display the number pattern in the below picture.
練習十一參考解法：
Exercise 11 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int n = 9;
for(int i = 1; i <= n; i++)
{
for(int j = 1; j <= i; j++)
printf("%d ", i * j);
printf("\n");
}
return 0;
}
練習十二：質數
設計可以輸入一個整數 N ，輸出到整數 N 的質數數列。例如當 N = 50 時，程式輸出：2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,
Exercise 12: Prime
Write a C program that gets an integer from user and display prime numbers up to N. If N is 50, the program should print: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,
練習十二參考解法：
Exercise 12 solution:
#include <stdio.h>
#include <stdlib.h>int main()
{
int n, isPrime;
printf("Enter an integer:");
scanf("%d", &n); for(int p = 2; p <= n; p++)
{
isPrime = 1;
for(int i = 2; i * i <= p; i++)
{
if(p % i == 0)
{
isPrime = 0;
break;
}
} if(isPrime == 1)
printf("%d, ", p);
} return 0;
}
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