字符串编程

1.从键盘上输入一字符串，计算里面连续数字串的和.如:”12qw32fds22” 输出12+32+22的和。

#include <stdio.h>
#define MAX_SIZE 30

int main()
{
    char str[MAX_SIZE];

    int i;
    int sum = 0;
    int result = 0;

    printf("Please input a string:\n");
    scanf("%s",str);

    for(i = 0; str[i] != '\0'; i++) 
    {                                          /* 编程总结:连续判断用while,单次判断用if,对比25行*/
        while(str[i] >= '0' && str[i] <= '9')
        {
            sum = sum * 10 + (str[i] - '0');
            i++;
        }

        result = result + sum;

        sum = 0;
    }

    printf("\nThe result is: %d\n",result);

    return 0;
}

2.从键盘输入一个整数，将这个整数转换成字符串输出。

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

int main()
{
    int num;
    int i;
    char temp;

    char str[20];

    printf("Please input a number:\n");
    scanf("%d",&num);

    for(i = 0; num != 0; i++)
    {
        str[i] = num % 10 + '0';
        num = num / 10;
    }

    str[i] = '\0';

    for(i = 0; i < strlen(str)/2; i++)//此处循环条件不加等号
    {
        temp = str[i];
        str[i] = str[strlen(str)-i-1];
        str[strlen(str)-i-1] = temp;
    }

    printf("The string is:%s\n",str);

    return 0;
}