[英]My for loop keeps looping and causes the program to crash
我正在尝试制作一个将接收字符串并输出大写版本的程序。 我的代码可以正常工作,但是一旦遍历字符串并对其进行更改,它立即崩溃,并且我不确定原因。 这是我的两段代码。
/*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;
}
您可以使用以下代码将字符串转换为大写
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");
或像这样使用
#include <algorithm>
#include <string>
std::string str = "Hello World";
std::transform(str.begin(), str.end(),str.begin(), ::toupper);
您正在中断该函数而未返回任何内容。 如果要使用break,请使用{}关闭循环
prog.cpp:16:5:错误:break语句不在循环或switch break中;
你的for循环还有一个额外的; 在末尾。
std::cout
和std::toupper
没用,因为您已经包含了namespace std;
以及为什么要使用break;
? 不需要它。 写吧
for (int i=0; i<str.length(); i++)
cout << toupper(str[i]);
删除中断;
您不转换字符串,而是在函数中输出其转换。
代替
std::cout << std::toupper(str[i]);
采用
str[i]=std::toupper(str[i]);
并将所有打印移出该功能。 更改字符串不包括打印!
也请注意@ 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;
}
编辑:请注意,保持函数签名如上( string toUpper ( string str)
,根据需要),我们正在制作一些额外的字符串副本,并且最重要的是:我们不修改原始字符串(执行代码并查看最后一cout
结果。
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