[C ++ Basics] 032_common string processing functions (strcat, strcpy, strcmp, strupr, strlwr, strlen)

1. strcat -- string connection

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "abcd"; 7     char str1[] = "abc"; 8     strcat(str, str1); 9     cout<<str<<endl;10 11     system("pause");12     return 0;13 }

※Note: the first string array must be large enough; otherwise, an out-of-bounds problem may occur.

2. strcpy -- Copy strings

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "abcd"; 7     char str1[] = "abc"; 8     strcpy(str, str1); 9     cout<<str<<endl;10 11     system("pause");12     return 0;13 }

※Note: the first string array must be large enough; otherwise, an out-of-bounds problem may occur. The second parameter can be an array or a character.

3. strcmp -- string comparison Function

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "abcd"; 7     char str1[] = "abc"; 8     if(0 == strcmp(str, str1)){ 9         cout<<"Equal."<<endl;10     }else{11         cout<<"Unequal."<<endl;12     }13 14     system("pause");15     return 0;16 }

※Note: if the former is large, 1 is returned. If the latter is large,-1 is returned. If the former is equal, 0 is returned.

4. strupr -- lowercase to uppercase

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "abcdf"; 7     char str1[] = "abcde"; 8     strupr(str); 9     cout<<str<<endl;10 11     system("pause");12     return 0;13 }

5. strlwr -- convert uppercase to lowercase

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "AASdf"; 7     strlwr(str); 8     cout<<str<<endl; 9 10     system("pause");11     return 0;12 }

 

6. strlen -- get the string length

 1 #include <iostream> 2 using namespace std; 3  4 int main(){ 5  6     char str[15] = "AASdf"; 7     cout<<strlen(str)<<endl; 8  9     system("pause");10     return 0;11 }