string类有哪些操作 字符串处理常用方法汇总

string str = "Hello";

string str(10, 'A');

char arr[] = {'H', 'e', 'l', 'l', 'o'}; string str(arr, 5);

string

find()

rfind()

find()

rfind()

string str = "This is a test string";
size_t pos = str.find("test"); // pos 的值为 10
if (pos != string::npos) {
    cout << "Found at position: " << pos << endl;
}

string::npos

find()

rfind()

find_first_of()

find_last_of()

find_first_not_of()

find_last_not_of()

find_first_of("aeiou")

+

append()

string str1 = "Hello";
string str2 = "World";
string result = str1 + " " + str2; // result 的值为 "Hello World"
str1.append(" ").append(str2); // str1 的值也变为 "Hello World"

append()

+

replace()

string str = "This is a test string";
str.replace(5, 2, "was"); // str 的值为 "This was a test string"

replace()

stringstream

stringstream

#include <sstream>
stringstream ss;
ss << "Hello" << " " << "World";
string result = ss.str(); // result 的值为 "Hello World"

==

!=

<

>

<=

>=

string str1 = "apple";
string str2 = "banana";
if (str1 < str2) {
    cout << "apple comes before banana" << endl;
}

tolower()

toupper()

compare()

compare()

string str1 = "apple";
string str2 = "Apple";
int result = str1.compare(str2); // result 的值不为 0，因为大小写不同
int result2 = str1.compare(0, 5, str2, 0, 5); // result2 的值为 0，因为指定了比较的字符数和起始位置

trim()

trim()

#include <algorithm>
#include <cctype>

string trim(const string& str) {
    size_t first = str.find_first_not_of(' ');
    if (string::npos == first) {
        return "";
    }
    size_t last = str.find_last_not_of(' ');
    return str.substr(first, (last - first + 1));
}

\

"

stoi()

stol()

stoll()

stof()

stod()

stold()

string str = "123";
int num = stoi(str); // num 的值为 123

to_string()

int num = 123;
string str = to_string(num); // str 的值为 "123"

try-catch

string

string str = "Hello";
for (string::iterator it = str.begin(); it != str.end(); ++it) {
    cout << *it << endl;
}

string str = "Hello";
for (char c : str) {
    cout << c << endl;
}

string str = "Hello";
for (string::iterator it = str.begin(); it != str.end(); ++it) {
    *it = toupper(*it);
} // str 的值为 "HELLO"