我正在编写一个程序,告诉用户输入一个随机字符串,然后打印出所有重复项以及每个重复项的次数。我通过 gdb 运行它,这是输出:
程序如下:
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main()
{
//Read a string word by word and put into a vector
//loop through the vector:
// If there are two words duplicate:
// loop through another vector (used to store duplicate word)
// compare if these two words are the same as the duplicate word stored
// If the same: ++count[i]
// If not: push_back(count) ; ++count[i]
string word;
vector<string> sentence;
vector<string> duplicate;
vector<int> times;
int count = 1;
while (cin >> word) {
if (word == "ctrlz") {
break;
}
sentence.push_back(word);
}
vector<string>::size_type i = 0;
vector<string>::size_type j = 0;
while (i != sentence.size()) {
if (sentence[i] == sentence[i+1]) {
while (j != sentence.size()) {
if (duplicate.size() == 0) {
duplicate.push_back(sentence[i]);
times.push_back(count);
++times[0];
}
else {
if (sentence[i] != duplicate[j]) {
duplicate.push_back(sentence[i]);
times.push_back(count);
++times[j+1];
}
else {
++times[j];
}
}
++j;
}
}
++i;
}
while (i != duplicate.size()) {
cout << duplicate[i] << ' ';
++i;
}
return 0;
}
运行 gdb 后我得到了这个:
(gdb) run
Starting program: /home/phongcao/C++/6.12
phong phong phong phong phong phong
ctrlz
Program received signal SIGSEGV, Segmentation fault.
0x001c58d9 in std::string::size() const () from /usr/lib/libstdc++.so.6
(gdb)
这个输出是什么意思?我该如何解决这个段错误?
最佳答案
一些错误:
if (sentence[i] == sentence[i+1]) {
您的循环允许 i 为 size()-1
- 所以你读的是 vector 句末尾的内容。
while (i != sentence.size()) {
while (j != sentence.size()) {
...
++j;
}
++i;
}
j 永远不会重置 - 外循环的下一次迭代将从 sentence.size()
开始- 你可能不想要那样。
你应该用 std::map<std::string, int>
来解决这个问题:
std::map<std::string, int> words;
while (cin >> word) {
if (word == "ctrlz") {
break;
}
words[word] += 1;
}
for (std::map<std::string>::const_iterator it = words.begin(); it != words.end(); ++it) {
if (it->second > 1) {
cout << it->second << " copies of " << it->first << endl;
}
}
关于c++ - std::string::size() const () 中的段错误?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5306349/