记录一些Linux C的常用库函数

我已经受不了每次用的时候去百度了，还百度不出来。。。。。

【数字字符串转换篇】

atof - convert a string to a double

#include <stdlib.h>

double atof(const char *nptr);

atoi, atol, atoll, atoq - convert a string to an integer

#include <stdlib.h>

int atoi(const char *nptr);
long atol(const char *nptr);
long long atoll(const char *nptr);
long long atoq(const char *nptr);

strtod, strtof, strtold - convert ASCII string to floating-point number

#include <stdlib.h>

double strtod(const char *nptr, char **endptr);
float strtof(const char *nptr, char **endptr);
long double strtold(const char *nptr, char **endptr);

strtoul, strtoull, strtouq - convert a string to an unsigned long integer

#include <stdlib.h>

unsigned long int strtoul(const char *nptr, char **endptr, int base);

unsigned long long int strtoull(const char *nptr, char **endptr, int base);

gcvt - convert a floating-point number to a string

#include <stdlib.h>

char *gcvt(double number, size_t ndigit, char *buf);

【字符串操作篇】

strtok, strtok_r - extract tokens from strings

#include <string.h>

char *strtok(char *str, const char *delim);

char *strtok_r(char *str, const char *delim, char **saveptr);

strcmp, strncmp - compare two strings

#include <string.h>

int strcmp(const char *s1, const char *s2);

int strncmp(const char *s1, const char *s2, size_t n);

strcasecmp, strncasecmp - compare two strings ignoring case

#include <strings.h>

int strcasecmp(const char *s1, const char *s2);

int strncasecmp(const char *s1, const char *s2, size_t n);

【网络字节篇】

htonl, htons, ntohl, ntohs - convert values between host and network byte order

#include <arpa/inet.h>

uint32_t htonl(uint32_t hostlong);

uint16_t htons(uint16_t hostshort);

uint32_t ntohl(uint32_t netlong);

uint16_t ntohs(uint16_t netshort);

【输出篇】

printf, fprintf, sprintf, snprintf, vprintf, vfprintf, vsprintf, vsnprintf - formatted output conversion

#include <stdio.h>

int printf(const char *format, ...);
int fprintf(FILE *stream, const char *format, ...);
int sprintf(char *str, const char *format, ...);
int snprintf(char *str, size_t size, const char *format, ...);

#include <stdarg.h>

int vprintf(const char *format, va_list ap);
int vfprintf(FILE *stream, const char *format, va_list ap);
int vsprintf(char *str, const char *format, va_list ap);
int vsnprintf(char *str, size_t size, const char *format, va_list ap);