第七章例7-14

#include<stdio.h>
int main(void)
{
    int  i,k;
    char str1[80],str2[80];
    long number;

    printf("Enter a string:");
    i = 0;
    while((str1[i] = getchar()) != '\n')
        i++;
    str1[i] = '\0';

    k=0;
    for(i = 0;str1[i] !='\0';i++)
        if
    (str1[i]>='0'&&str1[i]<='9'||str1[i]>='a'&&str1[i]<='f'||str1[i]>='A'&&str1[i]<='F')
        {
            str2[k] = str1[i];
            k++;
        }

    str2[k] = '\0';

    number = 0;
    for(i = 0;str2[i] !='\0';i++)
        if(str2[i] >='0' && str2[i] <='9')
            number = number * 16 + str2[i] - '0';
        else if(str2[i] >= 'a' && str2[i] <='f')
            number = number * 16 + str2[i] - 'a' + 10;
        else if(str2[i] >= 'A' && str2[i] <= 'F')
            number = number * 16 +str2[i] - 'A' + 10;

    printf("New string:");
    for(i=0;str2[i]!='\0';i++)
        putchar(str2[i]);
    printf("\n");
    printf("number = %ld\n",number);

    return 0;
}