题解 | 计算某字符出现次数

#include <string.h>
#include <stdio.h>
int main(void)
{
    char a[1000], b,c;
    char notspace = 1;
    int n = 0, cnt = 0;
    while ((a[n++] = getchar()) != '\n')
    {
        //printf("%d %c\n", n, a[n-1]);
        if(notspace)
        {
            if(a[n-1] == ' ')
            {
                return 0;
                printf("input error\n");
            }
            else
                notspace = 0;
        }
        if(n  > 1001)
        {
            return 0;
            printf("input error\n");
        }
    }
    a[n] = '\0';
    //printf("a is %s\n", a);
    b = getchar();
    //printf("%d %c\n", n, b);
    if((b <= 'z' && b >= 'a') || (b <= 'Z' && b >= 'A') || (b <= '9' && b >= '0'))
    {
        if((b <= '9' && b >= '0'))
        {
            for(int i = 0; i < strlen(a); i++)
            {
                if(a[i] == b) cnt++;
            }
        }

        if((b <= 'z' && b >= 'a'))
        {
            c = b - 'a' + 'A';
            for(int i = 0; i < strlen(a); i++)
            {
                if((a[i] == b) || (a[i] == c))
                    cnt++;
            }
        }

        if((b <= 'Z' && b >= 'A'))
        {
            c = b + 'a' - 'A';
            for(int i = 0; i < strlen(a); i++)
            {
                if((a[i] == b) || (a[i] == c))
                    cnt++;
            }
        }

    }
    else
    {
        return 0;
        printf("input error\n");
    }
    printf("%d", cnt);
    return 0;
}