嵌入式软件经典字符串面试、笔试题（基础）

平时自己用来温习的一些试题，如果有错误的地方，还望网友包涵和指正。

1.统计字符串中子字符串的个数。

#include <stdio.h>#include <string.h>int countCharNum(const char* FuString, const char* ZiString){    int countString = 0;    char* subString = ZiString;    if(*ZiString == NULL){        printf("Please Input Right Format SubString!\n");        return 0;    }    while(*FuString != NULL){        if(*FuString == *subString){            subString++;            if(*subString == NULL){//判断比较的子字符串是否结束                countString++;//计数子字符串相等的个数                subString = ZiString;            }        }else{            subString = ZiString;//只要比较的字符不相等，就重置指针指向子字符串的开始位置        }        FuString++;//遍历整个字符串    }    return countString;}int main(int argc,char* argv[]){    if(argc != 3){        printf("                       __________________________________\n");        printf("Please Input Format As |./countString  FuString  ZiString |\n");        printf("                       ----------------------------------\n");         return -1;    }    if(argc == 3){        int stringNumber = 0;        char* fuStr = argv[1];        char* subStr = argv[2];        stringNumber = countCharNum(fuStr,subStr);        printf("The Number Of  %s(SubString) In %s(FuString) Is: %d\n", subStr, fuStr, stringNumber);        return 0;    }}

测试结果如图：

2.基本数据类型所占用大小的问题

typedef struct hsmmc {         unsigned char res1[0x10];          unsigned int sysconfig;            unsigned int sysstatus;            unsigned char res2[0x14];          unsigned int con;           } hsmmc_t;          #define OMAP_HSMMC_BASE 0xe6000000          static hsmmc_t *mmc_base = (hsmmc_t *)OMAP_HSMMC_BASE;  

求&mmc_base-> sysstatus 的值？
某文Ku上的答案为0xe6000018，呵呵！！

#include <stdio.h>#define OMAP_HSMMC_BASE 0xe6000000typedef struct{                unsigned char res1[0x10];//占用十六进制0x10个字节大小                unsigned int sysconfig;//占用4个字节                unsigned int sysstatus;                unsigned char res2[0x14];                unsigned int con;        } hsmmc_t;//声明一个hsmmc_t的结构体指针指向0xe6000000地址static hsmmc_t* hsmmc = (hsmmc_t*) OMAP_HSMMC_BASE;int main(int argc,char* argv[]){    /*计算机环境不同可能有差异，我的测试环境是32位机*     *char：占用1个字节 -128~127                *     *unsigned char：占用1个字节 0~255          *     *int：占用4个字节 -32768~32767             *     *unsigned int:占用4个字节 0~65535          */    printf("sizeof(int) is:%d\nsizeof(unsiged int) is:%d\nsizeof(char) is:%d\nsizeof(unsigned char) is:%d\n", sizeof(int), sizeof(unsigned int), sizeof(char), sizeof(unsigned char));    printf("The Address of The struct hsmmc_t'sysstatus is: 0x%x\n", &hsmmc->sysstatus);    return 0;}

测试结果如图

3.倒油逻辑题

有三个油瓶，标号a,b,c，在装满时分别能盛7两、4两、3两油。现在a瓶中有7两油，假设在倒出倒入时油可以全部倒出。只使用三个瓶子，请倒出2两油。写出操作步（某题库没有作解答）
答案如图：