它在字符串中搜索与参数中指定的任何字符都不匹配的第一个字符。在这里，我们将描述它拥有的所有语法。
返回值：成功时第一个不匹配字符的索引；如果找不到这样的字符，则返回string::npos。
语法1：搜索不是字符串str元素的第一个字符。
size_type string::find_first_not_of (const string& str) const str:Another string with the set of characters to be used in the search.
// CPP code for find_first_not_of (const string& str) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str1, string str2)
{
// Finds first character in str1 which
// is not present in str2
string::size_type ch = str1.find_first_not_of(str2);
cout << "First unmatched character:";
cout << str1[ch];
}
// Driver code
int main()
{
string str1("Hello World!");
string str2("GeeksforGeeks");
cout << "Original String:" << str1 << endl;
cout << "String to be looked in:" << str2 << endl;
find_first_not_ofDemo(str1, str2);
return 0;
}输出：
Original String:Hello World! String to be looked in:GeeksforGeeks First unmatched character:H
语法2：从索引idx搜索不是字符串str元素的第一个字符。
size_type string::find_first_not_of (const string& str, size_type idx) const str:Another string with the set of characters to be used in the search. idx:is the index number from where we have to start finding first unmatched character.
// CPP code for string::find_first_not_of
// (const string& str, size_type idx) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str1, string str2)
{
// Finds first character in str1 from index 3 which
// is not present in str2
string::size_type ch = str1.find_first_not_of(str2, 3);
cout << "First unmatched character:";
cout << str1[ch];
}
// Driver code
int main()
{
string str1("geeKsforgeeks");
string str2("GeeksforGeeks");
cout << "Original String:" << str1 << endl;
cout << "String to be looked in:" << str2 << endl;
find_first_not_ofDemo(str1, str2);
return 0;
}输出：
Original String:geeKsforgeeks String to be looked in:GeeksforGeeks First unmatched character:K
语法3：搜索不是C-string cstr元素的第一个字符。
size_type string::find_first_not_of (const char* cstr) const cstr:Another C-string with the set of characters to be used in the search.
注意该cstr可能不是空指针(NULL)。
// CPP code for string::find_first_not_of (const char* cstr) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str)
{
// Finds first character in str which
// is not present in "geeksforgeeks"
string::size_type ch = str.find_first_not_of("geeksforgeeks");
cout << "First unmatched character:";
cout << str[ch];
}
// Driver code
int main()
{
string str("GeeksforGeeks");
cout << "Original String:" << str << endl;
find_first_not_ofDemo(str);
return 0;
}输出：
Original String:GeeksforGeeks First unmatched character:G
语法4：从索引idx搜索不是C-string cstr元素的第一个字符
size_type string::find_first_not_of (const char* cstr, size_type idx) const cstr:Another string with the set of characters to be used in the search. idx:is the index number from where we have to start finding first unmatched character.
注意该cstr可能不是空指针(NULL)。
// CPP code for size_type string::find_first_not_of
// (const char* cstr, size_type idx) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str)
{
// Finds first character in str from 5th index which
// is not present in "geeksforgeeks"
string::size_type ch = str.find_first_not_of("geeksForgeeks", 5);
cout << "First unmatched character:";
cout << str[ch];
}
// Driver code
int main()
{
string str("GeeksforGeeks");
cout << "Original String:" << str << endl;
find_first_not_ofDemo(str);
return 0;
}输出：
Original String:GeeksforGeeks First unmatched character:f
语法5：在str中查找不等于char c的第一个字符。
size_type string::find_first_not_of (char c) const c Character c with which contents of str are required to be compared.
// CPP code for size_type string::find_first_not_of (char c) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str)
{
// Finds first character in str which
// is not equal to character 'G'
string::size_type ch = str.find_first_not_of('G');
cout << "First unmatched character:";
cout << str[ch];
}
// Driver code
int main()
{
string str("GeeksforGeeks");
cout << "Original String:" << str << endl;
find_first_not_ofDemo(str);
return 0;
}输出：
Original String:GeeksforGeeks First unmatched character:e
语法6：从索引idx中查找不等于char c的str中的第一个字符。
size_type string::find_first_not_of (char c, size_type idx) const c: Character c with which contents of str are required to be compared. idx: index from where search of the first unmatched character is to be started
// CPP code for size_type string::find_first_not_of
// (char c, size_type idx) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str)
{
// Finds first character in str from 6th index which
// is not equal to character 'G'
string::size_type ch = str.find_first_not_of('G', 6);
cout << "First unmatched character:";
cout << str[ch];
}
// Driver code
int main()
{
string str("GeeksforGeeks");
cout << "Original String:" << str << endl;
find_first_not_ofDemo(str);
return 0;
}输出：
Original String:GeeksforGeeks First unmatched character:o
语法7：从索引idx开始，搜索也不是字符数组chars的chars_len字符的元素的第一个字符。
size_type string::find_first_not_of (const char* chars, size_type idx, size_type chars_len) const *chars:is the character array with which searching of first unmatched is to be performed. idx: index number in string chars_len:is the character length in *chars to be picked for searching purpose
// CPP code for size_type string::find_first_not_of
// (const char* chars, size_type idx, size_type chars_len) const
#include <iostream>
using namespace std;
// Function to demonstrate find_first_not_of
void find_first_not_ofDemo(string str)
{
// Finds first character in str from 4th index which
// is not equal to any of the first 3 characters from "svmnist"
string::size_type ch = str.find_first_not_of("svmnist", 4, 3);
cout << "First unmatched character:";
cout << str[ch];
}
// Driver code
int main()
{
string str("GeeksforGeeks");
cout << "Original String:" << str << endl;
find_first_not_ofDemo(str);
return 0;
}输出：
Original String:GeeksforGeeks First unmatched character:f
相关用法
注：本文由纯净天空筛选整理自 std::string::find_first_not_of in C++。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。