(ch1-ch2)>0?1:(ch1-ch2)==0?0:-1;
时间: 2024-03-10 09:44:51 浏览: 121
这是一个使用三目运算符的表达式,它的含义是:
如果 `ch1 - ch2` 大于 0,则返回 1;否则,如果 `ch1 - ch2` 等于 0,则返回 0;否则返回 -1。
该表达式相当于以下代码:
```
int result;
if (ch1 - ch2 > 0) {
result = 1;
} else if (ch1 - ch2 == 0) {
result = 0;
} else {
result = -1;
}
```
但是使用三目运算符可以使代码更加简洁。
相关问题
ch1 = ch2 = ch3 = 0;
这是三变量初始化的示例,在许多编程语言中,尤其是使用C、C++或者类似语法的语言,如JavaScript,这里`ch1`, `ch2`, 和 `ch3` 都被赋值为0。这种语句通常用于创建一个初始状态为零的字符数组或者是准备接收后续赋值的变量。每个`ch`代表一个字符变量,它们都被设置成整数值0,这意味着它们还没有存储任何字符信息。
这段代码用C++编写,解释这段代码并给出详细注释void HuffmanCoding::encode(ifstream& fIn) { unsigned long packCnt = 0, hold, maxPack = bytes * bits, pack = 0; char ch, ch2; int bitsLeft, runLength; for (fIn.get(ch); !fIn.eof();)//循环直到读到文件末尾 { for (runLength = 1, fIn.get(ch2); !fIn.eof() && ch2 == ch; runLength++) fIn.get(ch2);/* 获取runLength: 在读到当前字符ch的基础上继续读取,存进ch2中,并比较ch与ch2; 若ch==ch2,则为重复字符,runLength++;否则跳出循环 */ HuffmanNode* p = chars[(unsigned char)ch]; for (p = chars[(unsigned char)ch]; p != 0 && runLength != p->runLen; p = p->right); if (p == 0) cout<<("A promble in encode()"); if (p->codewordLen < maxPack - packCnt) { pack = (pack << p->codewordLen) | p->codeword; pack += p->codewordLen; } else { bitsLeft = maxPack - packCnt; pack <<= bitsLeft; if (bitsLeft != p->codewordLen) { hold = p->codeword; hold >>= p->codewordLen - bitsLeft; pack |= hold; } else pack |= hold; output(pack); if (bitsLeft != p->codewordLen) { pack = p->codeword; packCnt = maxPack - (p->codewordLen - bitsLeft); packCnt = p->codewordLen - bitsLeft; } else packCnt = 0; } ch = ch2; } if (packCnt != 0) { pack <<= maxPack - packCnt; output(pack); } }
这段代码实现了哈夫曼编码的压缩功能,对输入的文件进行编码并输出压缩后的二进制文件。
具体解释见代码注释:
```c++
void HuffmanCoding::encode(ifstream& fIn) {
// 初始化变量
unsigned long packCnt = 0, hold, maxPack = bytes * bits, pack = 0;
char ch, ch2;
int bitsLeft, runLength;
// 循环直到读到文件末尾
for (fIn.get(ch); !fIn.eof();) {
// 获取重复字符长度
for (runLength = 1, fIn.get(ch2); !fIn.eof() && ch2 == ch; runLength++)
fIn.get(ch2);
// 根据字符编码获取对应的哈夫曼编码
HuffmanNode* p = chars[(unsigned char)ch];
for (p = chars[(unsigned char)ch]; p != 0 && runLength != p->runLen; p = p->right);
if (p == 0)
cout<<("A promble in encode()");
// 判断编码是否能够直接放入压缩后的二进制文件中
if (p->codewordLen < maxPack - packCnt) {
pack = (pack << p->codewordLen) | p->codeword;
pack += p->codewordLen;
}
else {
// 将编码拆分为两部分,一部分放入当前二进制文件中,另一部分等待下一次输出
bitsLeft = maxPack - packCnt;
pack <<= bitsLeft;
if (bitsLeft != p->codewordLen) {
hold = p->codeword;
hold >>= p->codewordLen - bitsLeft;
pack |= hold;
}
else pack |= hold;
output(pack);
if (bitsLeft != p->codewordLen) {
pack = p->codeword;
packCnt = maxPack - (p->codewordLen - bitsLeft);
packCnt = p->codewordLen - bitsLeft;
}
else packCnt = 0;
}
ch = ch2; // 更新当前字符
}
// 输出剩余的编码
if (packCnt != 0) {
pack <<= maxPack - packCnt;
output(pack);
}
}
```
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