C语言中有哪些字符处理函数你知道吗

include <string.h>

char *strcat( char *str1, const char *str2 )

char *strncat( char *str1, const char *str2, size_t count );

char *strchr( const char *str, int ch )

char *strrchr( const char *str, int ch );

int strcmp( const char *str1, const char *str2 )

int strncmp( const char *str1, const char *str2, size_t count );

char *strcpy( char *dst, const char *src)

char *strncpy( char *dst, const char *src, size_t count );

size_t strlen( char *str )

#include <string.h>

void *memchr( const void *buffer, int ch, size_t count );

int memcmp( const void *buffer1, const void *buffer2, size_t count );

void *memcpy( void *dst, const void *src, size_t count );

void *memset( void *buffer, int ch, size_t count );

char *strstr( const char *str1, const char *str2 )

#include <stdio.h>
#include <string.h>
int main(void)
{
	char strA[20] = "hello world!", strB[20] = "world";
	char *tmp = strstr(strA, strB); 
	// (world!)
	printf("(%s)\n", tmp);
	return 0;
} 

#include <stdlib.h>

double strtod( const char *str, char **end )

long strtol( const char *str, char **end, int base )

unsigned long strtoul( const char *str, char **end, int base )

double atof( const char *str )

double atoi( const char *str )

double atol( const char *str )

#include <stdio.h>
int main(void)
{
	int num = 199;
	char str[20] = "";
	sprintf(str, "%d", num);
	// (199)
	printf("(%s)\n", str); 
	return 0;
} 

#include <stdio.h>
int main(void)
{
	int num = 199;
	char str[20] = "";
	sprintf(str, "%d", num);
	// (199)
	printf("(%s)\n", str); 
	return 0;
} 

char *strtok( char *str1, const char *str2 )

#include <stdio.h>
#include <string.h>
int main(void)
{
	char str[20] = "ABC|EDF|GH";
	char tmp[] = "|", *res = NULL;
	res = strtok(str, tmp);
	// (ABC) (EDF) (GH)
	while(res != NULL)
	{
		printf("(%s) ", res);
		res = strtok(NULL, tmp);
	}
	return 0;
} 

#include <ctype.h>
// 是否是数字字符
int isdigit( int ch )
// 是否是字母字符
int isalpha( int ch )
// 是否是小写字母
int islower( int ch )
// 转小写字母
int tolower( int ch )
// 是否是大写字母
int isupper( int ch );
// 转大写字母
int toupper( int ch )