我制作了一个程序，它接受用户输入的单词，将它们变成数字，运行计算然后将它们变回单词，这很简单，但是我的代码出错了。
每当我尝试输入一百或更高的值时，我得到输出“零”。 （很可能意味着我试图转换的数字是零，当它不应该是。）
由于这个原因，我认为问题在于计算函数“write_value”，但是，我不确定是什么。
我过去几个小时都在这里，所以它可能是我看不到的小东西，但它可能有几件事，所以不要浪费更多时间，我想我会把它贴在这里对于一些更有经验的人来看看。
提前感谢您的帮助。 ^^
示例输入将是： one_hundred_forty_four + two_hundred_thirty_eight
正确输出： three_hundred_eighty_two
电流输出： 零
当前代码：
using namespace std;
/**
* Map units digits into words
*
*/
string units[] = {
"", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
"ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen",
"seventeen", "eighteen", "nineteen"
};
/**
* Map tens digits into words
*/
string tens[] = {
"", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"
};
/**
* Splits a string into components
*
* @param words array for the components (assumed large enough)
* @param base the string to split
* @param separator the separator character
* @return pointer to the first unused element in the array
*/
string* split(string* words, string base, char separator) {
string* result = words;
istringstream input(base);
string token;
while (getline(input, token, separator)) {
if (token.length() > 0 && token != "and") {
if (token == "hundred") {
*--result += "_hundred";
*result++;
} else if (token == "thousand") {
*--result += "_thousand";
*result++;
} else if (token == "million") {
*--result += "_million";
*result++;
} else {
*result++ = token;
}
}
}
return result;
}
/**
* Joins an array of component strings into a single string
*
* @param words pointer to first component
* @param end pointer to the component beyond the last
* @param separator the separator character
* @return the joined string
*/
string join(string* words, string* end, char separator) {
string result;
if (words < end) {
result.append(*words);
for (string* w = words + 1; w < end; w++) {
result.append(separator + *w);
}
}
return result;
}
/**
* Writes number words into an array
*
* @param words array to store the words
* @param n the number to write
* @return pointer to the first unused element
*/
string* write_value(string* words, int n) {
string* result = words;
int t = (n % 100) / 10;
int u = (n % 10);
if (t == 1) { // fixes teens
t--;
u += 10;
}
if (t) {
*result++ = tens[t];
}
if (u) {
*result++ = units[u];
}
return result;
}
/**
* Reads an array of number words
*
* @param words the number words to read
* @param end pointer to the word beyond the last
* @return the value read
*/
int read_value(string* words, string* end) {
int result = 0;
string* w = words;
for (int i = 1; i < 10; i++) {
if (*w == tens[i]) {
result += 10 * i;
w += 1;
break;
}
}
for (int i = 1; i < 20; i++) {
if (*w == units[i]) {
result += i;
break;
}
}
return result;
}
/**
* Writes a number word string
*
* @param n the number to write
* @return the word string
*/
string Wordnum::write_number(int n) {
string result;
string words[20];
string* end;
if (n == 0) {
result = "zero";
} else if (n < 0) {
end = write_value(words, -n);
result = "negative_" + join(words, end, '_');
} else {
if (n > 100) {
end = write_value(words, n);
result = join(words, end, '_') + "hundred_";
} else if (n > 1000) {
end = write_value(words, n);
result = join(words, end, '_') + "thousand_";
} else if (n > 1000000) {
end = write_value(words, n);
result = join(words, end, '_') + "million_";
}
end = write_value(words, n);
result = join(words, end, '_');
}
return result;
}
/**
* Reads a number word string
*
* @param n the string to read
* @return the value read
*/
int Wordnum::read_number(string n) {
int result;
string words[20];
for (int i = 0; i < n.length(); i++) {
n[i] = tolower(n[i]);
if (n[i] == '-') n[i] = '_';
}
string* end = split(words, n, '_');
if (end == words || words[0] == "zero") {
result = 0;
} else if (words[0] == "negative") {
result = -read_value(words + 1, end);
} else {
result = read_value(words, end);
for (int i = 0; i < n.length(); i++) {
if (words[i] == "hundred") {
result = read_value(words - 1, end) * 100;
break;
} else if (words[i] == "thousand") {
result = read_value(words - 1, end) * 1000;
break;
} else if (words[i] == "million") {
result = read_value(words - 1, end) * 1000000;
break;
}
}
}
return result;
}
/**
* Inserts a Wordnum into an output stream as a word string
*
* @param os the stream to insert into
* @param n the value to insert
* @return the modified stream
*/
ostream& operator<<(ostream& os, const Wordnum& n) {
return os << Wordnum::write_number(n.value_);
}
/**
* Extracts a Wordnum in word string form from an input stream
*
* @param is the stream to extract from
* @param n the value to assign
* @return the modified stream
*/
istream& operator>>(istream& is, Wordnum& n) {
string text;
if (is >> text) {
n.value_ = Wordnum::read_number(text);
}
return is;
}
标题文件：
#ifndef WORDNUM_H_
#define WORDNUM_H_
#include <string>
#include <istream>
#include <ostream>
/**
* A class to read and write numbers in word form
*/
class Wordnum {
public:
/**
* Writes a number word string
*
* @param n the number to write
* @return the word string
*/
static std::string write_number(int n);
/**
* Reads a number word string
*
* @param n the string to read
* @return the value read
*/
static int read_number(std::string n);
/**
* Creates a new Wordnum for a given value
*
* @param n the value of the number
*/
Wordnum(int n = 0) {
value_ = n;
}
/**
* Creates a new Wordnum from a word string
*
* @param n the value of the number
*/
Wordnum(std::string n) {
value_ = read_number(n);
}
/**
* Creates a new Wordnum as a copy of another
*
* @param n the value to copy
*/
Wordnum(const Wordnum& n) {
value_ = n.value_;
}
/**
* Makes this equivalent to n
*
* @param n the value to copy
* @return the modified Wordnum
*/
Wordnum& operator =(const Wordnum& n) {
value_ = n.value_;
return *this;
}
/**
* Converts a Wordnum to an int
*
* @return the value as an int
*/
operator int () const {
return value_;
}
/**
* Converts a Wordnum to a string
*
* @return the value as a word string
*/
operator std::string() const {
return write_number(value_);
}
/**
* Inserts a Wordnum into an output stream as a word string
*
* @param os the stream to insert into
* @param n the value to insert
* @return the modified stream
*/
friend std::ostream& operator <<(std::ostream &os, const Wordnum& n);
/**
* Extracts a Wordnum in word string form from an input stream
*
* @param is the stream to extract from
* @param n the value to assign
* @return the modified stream
*/
friend std::istream& operator >>(std::istream &is, Wordnum& n);
/**
* Returns sum of n1 and n2
*/
friend Wordnum operator +(const Wordnum& n1, const Wordnum& n2) {
return Wordnum(n1.value_ + n2.value_);
}
/**
* Returns difference of n1 and n2
*/
friend Wordnum operator -(const Wordnum& n1, const Wordnum& n2) {
return Wordnum(n1.value_ - n2.value_);
}
/**
* Returns product of n1 and n2
*/
friend Wordnum operator *(const Wordnum& n1, const Wordnum& n2) {
return Wordnum(n1.value_ * n2.value_);
}
/**
* Returns quotient of n1 and n2
*/
friend Wordnum operator /(const Wordnum& n1, const Wordnum& n2) {
return Wordnum(n1.value_ / n2.value_);
}
private:
int value_;
};
#endif
答案 0 :(得分：0)
从字符转换为整数并不是直截了当的 char *（cstring）是一个char数组， 其中每个元素的大小为一个字节（8位）
整数是4个字节（32位），因此， 正确地从char转换为int你 必须用char填充4个字节中的每一个。 换句话说，你需要4个字符才能生成一个int。
好像这还不够，还有另外一个因素 这需要考虑在内。 字节序 （我会把它留给你看看）你的 需要考虑系统。Endianness决定系统如何存储数据。 例如，以16位整数表示存储数字2 您的系统可以通过以下两种方式之一存储它：
方式1：00000010 00000000
方式2：00000000 00000010
因为16位整数可以存储在2个字节中 要么是从右到左，要么从左到右。 Here 是一张照片。
这是执行endian检查所需的代码 从char *（cstring）转换为int（32位整数）
bool isBigEndian(){
int a = 1;
return !((char*)&a)[0];
}
int convertToInt(char *charArr, int len){ //len should be <= 4
int a = 0;
if(!isBigEndian())
for(int i = 0; i < len; i++)
((char*)&a)[i] = charArr[i];
else
for(int i = 0; i < len; i++)
((char*)&a)[3-i] = charArr[i];
return a;
}
因为代码适用于大小为4或更小的char *数组，任何更多的代码都不起作用 因为整数不能超过4个字节。我建议查看big endian vs little endian 在你看代码之前它会更有意义。如果你直截了当地知道这是怎么做的，你可以转换为其他类型的常规int，你可以转换为Uint16（16位）或Uint8（8位;完美的大小，一次存储一个char;）
我希望你现在已经解决了这个问题，如果没有，希望这会有所帮助。