1. 字符串轉(zhuǎn)換為 unsigned int 類型

/*將傳入的字符串轉(zhuǎn)換為無符號的的32位整形
 *@param: str : 傳入的字符串
 *retval: The converted value.
*/
static unsigned int atoui(const char *str);

unsigned int atoui(const char *str)
{
    unsigned int result = 0, i = 0;
    char *tmp = NULL;
    for (i = 0; isspace(str[i]) && i < strlen(str); i++)//跳過空白符;    
        ;
    tmp = str+i;
    while (*tmp)
    {
        result = result * 10 + *tmp - '0';
        tmp++;
    }

    return result;
}

2. 將uint32 類型轉(zhuǎn)換為 C字符串, 默認采用 10進制

char* uitoa(unsigned int n, char *s)
{
    int i, j;
    i = 0;
    char buf[20];
    memset(buf, 0, sizeof(buf));
    do{
        buf[i++] = n % 10 + '0';//取下一個數(shù)字
    } while ((n /= 10)>0);//刪除該數(shù)字   
    i -= 1;
    for (j = 0; i >= 0; j++, i--)//生成的數(shù)字是逆序的,，所以要逆序輸出
        s[j] = buf[i];
    s[j] = '\0';    
    return s;
}

3. 自定義LOG輸出宏函數(shù),

 #define myprint( x...) do {char bufMessagePut_Stdout_[1024];            sprintf(bufMessagePut_Stdout_, x);            fprintf(stdout, "%s [%d], [%s]\n", bufMessagePut_Stdout_,__LINE__, __FILE__ );    }while (0)   

 int main()
 {   
             myprint("The num : %d, The string : %s", 98, "nihao");
             return 0;
 } 

//該函數(shù)宏要注意的地方: 宏中的局部參數(shù): bufMessagePut_Stdout_, 不可以與外面的傳進參數(shù)同名 ,同名時,宏替換會產(chǎn)生歧義:
sprintf(bufMessagePut_Stdout_, "%s", bufMessagePut_Stdout_);
此時: 前后bufMessagePut_Stdout_應(yīng)代表不同的參數(shù)類型及意義,而程序上并不會這樣認為. 

4.將C風格 16進制的字符串 轉(zhuǎn)換為十進制(即: 默認字符串中存的內(nèi)容為 16進制數(shù)據(jù))

//獲取x的y次方; x^y
unsigned int power(int x, int y)
{
    unsigned int result = 1;
    while (y--)
        result *= x;
    return result;
}
//將字符串的內(nèi)容轉(zhuǎn)換為 16進制
unsigned int hex_conver_dec(char *src)
{
    char *tmp = src;
    int len = 0;
    unsigned int hexad = 0;
    char sub = 0;

    while (1)
    {
        if (*tmp == '0')            //去除字符串 首位0
        {
            tmp++;
            continue;
        }           
        else if (*tmp == 'X')
        {
            tmp++;
            continue;
        }
        else if (*tmp == 'x')
        {
            tmp++;
            continue;
        }
        else
            break;

    }

    len = strlen(tmp);
    for (len; len > 0; len--)
    {        
        sub = toupper(*tmp++) - '0';
        if (sub > 9)
            sub -= 7;
        hexad += sub * power(16, len - 1);      
    }

    return hexad;
}
int main(){
    hex_conver_dec("31");    //49
    hex_conver_dec("abcd02");    //11259138
}

5.在一塊內(nèi)存中查找子串位置：該函數(shù)主要是為了在二進制文本中進行查找操作,。

//獲取字符流中的指定子串的位置
char* memstr(char* full_data, int full_data_len, char* substr) 
{ 
     if (full_data == NULL || full_data_len <= 0 || substr == NULL) { 
         return NULL; 
     } 
     if (*substr == '\0') { 
         return NULL; 
     } 
     int sublen = strlen(substr); 
     int i; 
     char* cur = full_data; 
     int last_possible = full_data_len - sublen + 1; 
     for (i = 0; i < last_possible; i++) { 
         if (*cur == *substr) { 
             //assert(full_data_len - i >= sublen);  
             if (memcmp(cur, substr, sublen) == 0) { 
                 //found  
                 return cur; 
             } 
        } 
         cur++; 
     }                                                                                                                                                    

     return NULL;
 }

6. 查看指定目錄下的文件是否存在

bool if_file_exist(const char *filePath)
{
    if(filePath == NULL)
        assert(0);
    if(access(filePath, F_OK) == 0)
        return true;

    return false;
}

7. 將unsigned int 轉(zhuǎn)換為16進制C字符串

char *unsigned_int_to_hex(unsigned int number, char *hex_str)
{
    char b[17] = { "0123456789ABCDEF" };
    int c[8], i = 0, j = 0, d, base = 16;

    do{
        c[i] = number % base;
        i++;
        number = number / base;
    } while (number != 0);

    hex_str[j++] = '0';
    hex_str[j++] = 'X';

    for (--i ; i >= 0; --i, j++)
    {
        d = c[i];
        hex_str[j] = b[d];
    }
    hex_str[j] = '\0';

    return hex_str;
}