[英]My for loop keeps looping and causes the program to crash
我正在嘗試制作一個將接收字符串並輸出大寫版本的程序。 我的代碼可以正常工作,但是一旦遍歷字符串並對其進行更改,它立即崩潰,並且我不確定原因。 這是我的兩段代碼。
/*This program is to intended to receive a string and return a version of it in all upper case*/
#include <iostream>
#include <string>
#include <locale>
using namespace std;
string toUpper ( string str)
{
cout <<"\n"; //Puts spaces between the input and output
for (int i=0; i<str.length(); i++;)
std::cout << std::toupper(str[i]); //A loop which goes through each digit of the string
break;
cout <<"\n\n"; //Creates spaces after the output
return str;
}
/*This program calls a function to make a string in upper case*/
#include <iostream>
#include <string>
#include <sstream>
#include <locale>
#include "toUpper1.h" //Calls the header file which contains the loop
using namespace std;
int main ()
{
cout<<"\nPlease type in a word\n\n";
string input; //Creates a variable of cin that can be used in the toUpper command
cin>>input; //Makes a user input command part of the declared variable
cout<<toUpper(input); //The command that causes the user input string to be transformed into upper case
return 0;
}
您可以使用以下代碼將字符串轉換為大寫
Boost字符串算法:
#include <boost/algorithm/string.hpp>
#include <string>
std::string str = "Hello World";
boost::to_upper(str);
std::string newstr = boost::to_upper_copy("Hello World");
或像這樣使用
#include <algorithm>
#include <string>
std::string str = "Hello World";
std::transform(str.begin(), str.end(),str.begin(), ::toupper);
您正在中斷該函數而未返回任何內容。 如果要使用break,請使用{}關閉循環
prog.cpp:16:5:錯誤:break語句不在循環或switch break中;
你的for循環還有一個額外的; 在末尾。
std::cout
和std::toupper
沒用,因為您已經包含了namespace std;
以及為什么要使用break;
? 不需要它。 寫吧
for (int i=0; i<str.length(); i++)
cout << toupper(str[i]);
刪除中斷;
您不轉換字符串,而是在函數中輸出其轉換。
代替
std::cout << std::toupper(str[i]);
采用
str[i]=std::toupper(str[i]);
並將所有打印移出該功能。 更改字符串不包括打印!
也請注意@ bbdude95的答案。
代替
cout<<"\nPlease type in a word\n\n";
string input; //Creates a variable of cin that can be used in the toUpper command
cin>>input;
采用
char input[256];
cout << "Please type in a word:\n>";
cin.getline( input, 256, '\n' );
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
string toUpper ( string str)
{
cout <<"\n"; //Puts spaces between the input and output
for (int i=0; i<str.length(); i++)
str[i] = std::toupper(str[i]); //A loop which goes through each digit of the string
//break;
cout <<"\n\n"; //Creates spaces after the output
return str;
}
int main ()
{
cout<<"\nPlease type in a word\n\n";
string input; //Creates a variable of cin that can be used in the toUpper command
cin>>input; //Makes a user input command part of the declared variable
//The command that causes the user input string to be transformed into uppe case
cout << toUpper(input);
cout << std::endl << "The original string is" << input << std::endl;
return 0;
}
編輯:請注意,保持函數簽名如上( string toUpper ( string str)
,根據需要),我們正在制作一些額外的字符串副本,並且最重要的是:我們不修改原始字符串(執行代碼並查看最后一cout
結果。
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