c_cpp CPP - 教程006 - 练习题

Posted 2021-05-14

#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <numeric>
#include <sstream>

// Function Prototypes
std::vector<std::string> StringToVector(std::string, 
        char separator);

std::string VectorToString(std::vector<std::string>& vec,
        char separator);

std::string TrimWhitespace(std::string);

std::vector<int> FindSubstringMatches(std::string theString,
        std::string substring);

std::string ReplaceAllSubstrings(std::string theString,
        std::string substring, std::string newString);

int main() {
    
    // ----- 1. CONVERT STRING TO VECTOR -----
    // Create a function that receives a string and separator
    // and returns a string vector
    std::string sSentence = "This is a random string";
    
    // Create a vector
    std::vector<std::string> vec = StringToVector(sSentence, ' ');
    
    // Cycle through each index in the vector and print
    // out each word 
    for(int i = 0; i < vec.size(); ++i){
        std::cout << vec[i] << "\n";
    }
    // ----- END PROBLEM CONVERT STRING TO VECTOR -----
    
    // ----- 2. PROBLEM CONVERT VECTOR TO STRING -----
    std::vector<std::string> vCusts(3);
    vCusts[0] = "Bob";
    vCusts[1] = "Sue";
    vCusts[2] = "Tom";
    
    std::string sCusts = VectorToString(vCusts, ' ');
    std::cout << sCusts << "\n";
    
    // ----- END PROBLEM CONVERT VECTOR TO STRING -----
    
    // ----- 3. STRIP WHITESPACE -----
    std::string aStr = "   Just some random words   ";
    
    aStr = TrimWhitespace(aStr);
    
    std::cout << "*" << aStr << "*\n";
    
    // ----- END STRIP WHITESPACE -----
    
    // ----- 4. PROBLEM FIND ALL INDEX MATCHES RETURN VECTOR -----
    std::string phrase = "To be or not to be";
    
    std::vector<int> matches = FindSubstringMatches(phrase, "be");
    
    for(int i = 0; i < matches.size(); ++i){
        std::cout << matches[i] << "\n";
    }
    // ----- END PROBLEM FIND ALL INDEX MATCHES RETURN VECTOR -----
    
    // ----- 5. PROBLEM REPLACE ALL SUBSTRINGS -----
    std::cout << ReplaceAllSubstrings("to know or not to know",
            "know", "be") << "\n";        
            
    // ----- END PROBLEM REPLACE ALL SUBSTRINGS -----
    
    // ----- 6. CHARACTER FUNCTIONS -----
    char letterZ = 'z';
    char num3 = '3';
    char aSpace = ' ';
    
    std::cout << "Is z a letter or number " << 
            isalnum(letterZ) << "\n";
    std::cout << "Is z a letter " << 
            isalpha(letterZ) << "\n";
    std::cout << "Is z uppercase " << 
            isupper(letterZ) << "\n";
    std::cout << "Is z lowercase " << 
            islower(letterZ) << "\n";
    std::cout << "Is 3 a number " << 
            isdigit(num3) << "\n";
    std::cout << "Is space a space " << 
            isspace(aSpace) << "\n";
    
    // ----- END CHARACTER FUNCTIONS -----
    
    return 0;
    
}

// ----- 1. CONVERT STRING TO VECTOR -----
std::vector<std::string> StringToVector(std::string, 
        char separator){
    std::string sSentence = "This is a random string";
    
    // Create a vector
    std::vector<std::string> vecsWords;
    
    // A stringstream object receives strings separated
    // by a space and then spits them out 1 by 1
    std::stringstream ss(sSentence);
    
    // Will temporarily hold each word in the string
    std::string sIndivStr;
    
    // While there are more words to extract keep
    // executing
    // getline takes strings from a stream of words stored
    // in the stream and each time it finds a blanks space
    // it stores the word proceeding the space in sIndivStr
    while(getline(ss, sIndivStr, separator)){
        
        // Put the string into a vector
        vecsWords.push_back(sIndivStr);
    }
    
    return vecsWords;
}
// ----- END CONVERT STRING TO VECTOR -----

// ----- 2. PROBLEM CONVERT VECTOR TO STRING -----
std::string VectorToString(std::vector<std::string>& vec,
        char separator){
    
    std::string theString = "";
    for(auto cust: vec)
        theString += cust + separator;
    
    return theString;
    
}
// ----- END PROBLEM CONVERT VECTOR TO STRING -----

// ----- 3. STRIP WHITESPACE -----
std::string TrimWhitespace(std::string theString){
    // find_last_not_of finds the last character
    // that doesn't match a list of defined characters
    std::string whitespaces(" \t\f\n\r");
    theString.erase(theString.find_last_not_of(whitespaces) + 1);
    
    // find_first_not_of does the same for the front of the string
    theString.erase(0, theString.find_first_not_of(whitespaces));
    
    return theString;
}
// ----- END STRIP WHITESPACE -----

// ----- 4. PROBLEM FIND ALL INDEX MATCHES RETURN VECTOR -----
std::vector<int> FindSubstringMatches(std::string theString,
        std::string substring){
    std::vector<int> matchingIndexes;
    
    // Check for matching substring
    int index = theString.find(substring, 0);
    
    // Keep adding indexes until none are left
    while(index != std::string::npos){
        matchingIndexes.push_back(index);
        index = theString.find(substring, index + 1);
    }
    
    return matchingIndexes;
}

// ----- END PROBLEM FIND ALL INDEX MATCHES RETURN VECTOR -----

// ----- 5. PROBLEM REPLACE ALL SUBSTRINGS -----
std::string ReplaceAllSubstrings(std::string theString,
        std::string substring, std::string newString){
    
    // Get a vector that contains all matching indexes
    std::vector<int> matches = FindSubstringMatches(theString, 
            substring);
    
    if(matches.size() != 0){
        // Get size difference between substring and newString
        int lengthDifference = newString.size() - substring.size();
        
        // Times through loop
        int timesLooped = 0;
         
        for(auto index: matches){
            theString.replace(index + (timesLooped * lengthDifference),
                    substring.size(),
                    newString);
            timesLooped++;
        }
    }
    
    return theString;
    
}
// ----- END PROBLEM REPLACE ALL SUBSTRINGS -----