CString、char字符串算法实例（含求长度、截取）

1、CString

检查字符串合法性：比如全是数字

CString.SpanIncluding("0123456789");

1、CStringW和CStringA

	CStringW CW = "汉字";
	CStringA CA = "汉字";
	std::cout<<"sizeof(CW)="<<sizeof(CW)<<std::endl;
	std::cout<<"sizeof(CA)="<<sizeof(CA)<<std::endl;
	std::cout<<"CW.GetLength()="<<CW.GetLength()<<std::endl;
	std::cout<<"CA.GetLength()="<<CA.GetLength()<<std::endl;

结果：
sizeof(CW)=8
sizeof(CA)=8
CW.GetLength()=2
CA.GetLength()=4

2、wchar_t和char

2.1 求长度

	wchar_t wCW[] = "汉字";
	char aCA[] = "汉字";
	std::cout<<"sizeof(wCW)="<<sizeof(wCW)<<std::endl;
	std::cout<<"sizeof(CA)="<<sizeof(CA)<<std::endl;
	std::cout<<"wcslen(wCW)="<<wcslen(wCW)<<std::endl;
	std::cout<<"strlen(aCA)="<<strlen(aCA)<<std::endl;

结果：
sizeof(wCW)=6
sizeof(CA)=5
wcslen(wCW)=2
strlen(aCA)=4

2.2 截取字符串

2.2.1 取后多少位

    char* cStr = "我以我血见轩辕！";
    char* strPos="我以我血";
    int n = strlen(strPos);
	char *temp = cStr+n;
	cout << temp << endl;

2.2.2 取前多少位

    char* cStr = "我以我血见轩辕！";
     char* strPos="见轩辕";
     
    char result[13];  // 创建一个字符数组来存储前四个字符，加1是为了存储字符串结束符'\0'
    strncpy(result, cStr, strlen(strPos)); // 复制前12个字节
    result[12] = '\0';         // 添加字符串结束符
    printf("前四个字符: %s\n", result);