for循环结构

for循环结构

1.

使用for循环结构求1-100之间的和值

    /*
     * filename: add.c
     *
     * function: 1+2+3+...+100 = ?
     *
     * author: YourName
     *
     * version: 0.1
     *
     * date: 2011-10-26
     *
     */


    #include <stdio.h>

    int main(int argc, const char *argv[])
    {
            int i, sum = 0;

            for (i = 1; i <= 100; i++)
            {
                    sum += i;
            }

            printf("1+2+3+...+100 = %d\n", sum);

            return 0;
    }

2.

将指定字符串中的大写字母转小写，小写字母转大写

    /*
     * filename: convert.c
     *
     * function: convert A to a and convert b to B in a string
     *
     * date: 2011-10-26
     */


    #include <stdio.h>
    #include <string.h>

    #define N 1024

    char convert(char ch)
    {
            if ((ch >= 'a') && (ch <= 'z'))
                    return ch - 32;
            else if ((ch >= 'A') && (ch <= 'Z'))
                    return ch + 32;
            else
                    return ch;
    }

    int main(int argc, const char *argv[])
    {
            char arr[N] = "AKAedu 123 heLLO!";
            int i, len = strlen(arr);

            printf("%s\n\n", arr);
            for (i = 0; i < len; i++)
            {
                    arr[i] = convert(arr[i]);
            }

            printf("After convert...\n\n");
            printf("%s\n", arr);
            
            return 0;
    }

3.

使用for循环求取10个数中的最大值

    /*
     * filename: max.c
     *
     * function: find max in num[N]
     *
     * author: Yourname
     *
     * version: 0.1
     *
     * date: 2011-10-26
     *
     */

    #include <stdio.h>

    #define N 10

    int main(int argc, const char *argv[])
    {
            int num[N] = {12,6,34,65,67,87,89,100,1,66};
            int i, max = 0;

            for (i = 0; i < 10; i++)
            {
                    if (max < num[i])
                    {
                            max = num[i];
                    }
            }

            printf("max is %d\n", max);

            return 0;
    }

4.

打印一个简单的两列的平方表

    /*
     * filename: suare,c
     *
     * function: ptint a table of square using a for statement
     *
     * author: YourName
     *
     * version: 0.1
     *
     * date: 2011-10-27
     *
     */

    #include <stdio.h>

    int main(int argc, const char *argv[])
    {
            int i, n;

            printf("this program print a table of square\n");
            printf("Enter number of entries in table: ");
            scanf("%d", &n);

            for (i = 1; i <= n; i++)
            {
                    printf("%10d%10d\n", i, i*i);
            }


            return 0;
    
    }

5.

输出半个菱形

    #include <stdio.h>

    int main(int argc, const char *argv[])
    {
            int i, j, k;
            int n;

            while (scanf("%d", &n))
            {
                    if (n & 1)
                            break;
                    k = n / 2;

                    for (i = -k; i <= k; i++)
                    {
                            if (i < 0)
                            {
                                    for (j = 0; j < i+k+1; j++)
                                            printf("*");
                            }
                            else
                            {
                                    for (j = 0; j < -i+k+1; j++)
                                            printf("*");
                            }
                            printf("\n");
                    }
                    

            }

            return 0;
    }