C++ basic review series — sun bujian 1208
C++ basic review series 01 (input/output class, calling mathematical function class)
C++ basics review series 2 (print graphics (loop), classic problems)
C++ basic review series 3 (recursive algorithm) {Fibonacci function, Hanoi issues}
C++ basics review series 4 (summary of scattered data)
C++ basics review series 5
Six, scattered knowledge points
How can I type “\n” cout<<“\n”<<endl;
As for data types, do not blindly int, double and longlong
Strlen () int len=sizeof(a)/sizeof(int);
# define macro definition
Char c = ‘A’; cout << char(c+j%26);
Digital black hole 6174
About utility Functions
- #include
- Double floor (double x)
- Double ceil(double x)
- #include
- Isalpha (a[I]) Identifies a letter. Isdigit (a[I]) identifies a number
- Isupper (a[I]) Determines whether to use upper case. Islower (a[I]) Determines whether to use lower case
- Isdigit (char c) Function: Checks whether the parameter is a decimal digit character. It is used to check whether c is a digit. If c ranges from 0 to 9, a non-zero value is returned; otherwise, a NULL value is returned. You can loop through an array of characters to determine each item
- Islower (char c) Function: Checks whether c is a lowercase letter. If c is a lowercase letter, return TRUE. Otherwise, return NULL(0).
- Isalpha (char c) #include
Isalpha (char c) #include
- Isupper (char c) function: Determines whether c is an uppercase letter. If c is an uppercase letter (a-Z), A non-zero value is returned. Otherwise, zero is returned.
- Int GCD (int a,int b){return b? gcd(b,a%b):a; }
- LCM = a * b/GCD (a,b)
#include char s[100]; int x=atoi(s); The above two lines also convert s to a number.
String Manipulation: 8 Common String manipulation functions <string.h>
Array assignment: memset(start address, set value, offset, or size x);
1. Puts function — Functions that print strings are typically of the form puts(string group)
Function: Prints a string to a terminal. For example, char a[n] and give the initial value, calls puts(array name) and prints the string.
General form: gets(array of characters)
Action: Input a string from a terminal to an array of characters and get a function value as the starting address of the array. Gets (array name) does the keyboard input. Note: the puts and gets functions can output or input only one string.
3, strcat — the general ‘form of the string concatenation function: strcat(array 1, array 2);
Concatenation: concatenates strings from two string arrays, concatenating string 2 to string 1. Note: The character array 1 must be large enough to hold the concatenated string.
Strcpy (string 1, string 2); strncpy (string 1, string 2)
Char str1[10], str2[]=”DongTeng”; strcpy(str1,str2); The result: str1 is the contents of STR2
Pay attention to
- A. You cannot assign a string constant or a character array directly to a character array
- B. Characters at the specified position can be assigned with strncpy. Strncpy (str1, str2, 3); Copy the third character from str2 to str1.
General form: STRCMP (string 1, string 2);
Use: To compare the difference between two strings. There are different rules of comparison.
strcmp(s1, s2); Return 0 if s1 and s2 are the same;
Return less than 0 if s1<s2; Returns a value greater than 0 if s1>s2.
Strlen — a function that measures the length of a string
7. STRLWR function — converts to lowercase function general form: STRLWR (string);
Strupr function — Converts to uppercase function general form: strupr(string). Char s[107]; cin >> s; Enter cine.get (s, 107) when Spaces end; Enter the end of the input input a number after the enter will be entered again when the input character will be carriage return interference so need to solve the problem of eating carriage return for example
cin>>n;
char a[100][1000];
for(int i=0;i<=n-1;i++)
{ cin.get();//吃回车
cin.get(a[i],1000);}
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