#include＜string.h＞ contains the function description

Common functions:　

Function name strcpy

Function copies one string to another

Original function char *strcpy(char *destin, char *source);

Example

char str[10];

char *str1="abcde";

strcpy(str,str1);

str contains "abcde"

This copies str1 to str

Function name strncpy

The function copies up to n characters in the string src to the character array dest (it does not stop copying when it encounters NULL like strcpy, but waits until n characters are collected before starting copying), and returns a pointer to dest. Note that it will overwrite previous characters.

Original function char *strncpy(char *dest, char *src,n);

Example

str[10]="abcdef",str1[10]="12345";

strncpy(str,str1,3); then str contains "123def"

Function name strcat

Function string concatenation function

Usage: char *strcat(char *destin, char *source);

Example

str[10]="abcdef",str1[10]="12345";

strcat(str,str1); then str contains "abcde12345"

Function name strcmp

Function string comparison

usage

intstrcmp(char *str1, char *str2);

If two strings are equal, return 0;

Example  

Function name strlen

Function strlen function finds the length of a string. It counts from the beginning of the string until it encounters the first ''. If you only define it without assigning an initial value, the result is uncertain. It will count from the beginning of the string until it encounters a ''.

usage  

Example  

Function name strnicmp

This function compares a part of a string to another string, regardless of case. 

Usage: strnicmp(char *str1, char *str2, unsigned maxlen);

For example, strnicmp(str1,str2,3) compares the first three characters of the latter string with the former string. If the characters are greater than the former, -1 is returned; if the characters are less than the former, 1 is returned; if the characters are equal, 0 is returned.

Function name stricmp

Function to compare two strings in a case-insensitive manner (don't understand)

Usage: int stricmp(char *str1, char *str2);

Example  

Function name strcmpi

This function compares one string to another, regardless of case.

Usage: int strcmpi(char *str1, char *str2);

Example  

Function name strrev

Function string reversal

Usage: char *strrev(char *str);

Example  

Function name strtod

Function to convert a string into a double value

Usage: double strtod(char *str, char **endptr);

Description Convert the initial string of numbers into double type

Example

char input[90],*end;

gets(input);

double value=strtod(intput,&end);

Function name strtol

Function to convert a string to a long integer

Usage: longstrtol(char *str, char **endptr, int base);

Example  

Function name

strupr

Function to convert lowercase letters in a string to uppercase letters

Usage: char *strupr(char *str);

Example  

Function name strchr

This function finds the first occurrence of a given character in a string.

Usage: char *strchr(char *str, char c);

Example  

Function name strcspn

This function finds the first segment with a given character set in a string.

Usage: int strcspn(char *str1, char *str2);

Example  

Function name strdup

The function copies the string to the newly created location

Usage: char *strdup(char *str);

Example  

Function name strerror

The function returns a pointer to an error message string.

Usage: char *strerror(int errnum);

Example  

Function name strnset

This function sets all characters in a string to the specified characters.

Usage: char *strnset(char *str, char ch, unsigned n);

Example  

Function name strpbrk

This function searches for characters in a given character set in a string.

Usage: char *strpbrk(char *str1, char *str2);

Example  

Function name strrchr

This function finds the last occurrence of a specified character in a string.

Usage: char *strrchr(char *str, char c);

Example  

Function name strstr

This function finds the first occurrence of a specified string in a string.

Usage: char *strstr(char *str1, char *str2);

Example  

Function name strtok

This function searches for words separated by the delimiter specified in the second string.

Usage: char *strtok(char *str1, char *str2);

Example  

Function name swab

Function swap byte

Usage: void swab (char *from, char *to, int nbytes);

Example