Summarize and organize the common library functions of C language in Linux----memory and string control and operation

In the absence of an IDE, it is necessary to remember the function names, parameters, basic usage, and considerations of some commonly used library functions.

Referring to the Linux_c_hs.chm directory, I have roughly divided the usual functions into several categories:

• 1. Memory and string control and operation
• 2. String conversions
• 3. Character test
• 4. File operation
• 5. Time and date
• 6. Common mathematical functions
• 7. File Content operation
• 8. File Permissions Control
• 9. Process Operations
• 10. Threading Operations
• One. Socket operation
• 12. Signal Processing
• 13. Data structures and algorithms

The following is an inductive collation of the first memory and string control and manipulation .

• A function collation that is deprecated

**function name use substitution scheme*1.intBCMP (Const void(SS,Const void*s2, size_t N); Comparebytesequences memcmp**2.voidBcopy (Const void*SRC,void*dest, size_t N); Copybytesequence memcpy Or memmove**3.voidBzero (void*s, size_t N); Write zero-Valued bytes Memset**4.Char*index (Const Char*s,intc); Locate characterinch stringSTRCHR**5.Char*rindex (Const Char*s,intc); Locate characterinch stringSTRRCHR*

• Memory or string lookup function collation

*Function Name Purpose Note*1.void*MEMCHR (Const void*s,intC, size_t N); Scan memory forA character (Forward)returnA pointer to the matchingbyteor NULLifThe character Doe s not occurinchThe given memory area.**2.void*MEMRCHR (Const void*s,intC, size_t N); Scan memory forA character (backward)returnA pointer to the matchingbyteor NULLifThe character Doe s not occurinchThe given memory area.**3.Char*STRCHR (Const Char*s,intc); Locate characterinch string(Forward)returnA pointer to the matched character or NULLifThe character  isNot found.**4.Char*STRRCHR (Const Char*s,intc); Locate characterinch string(backward)returnA pointer to the matched character or NULLifThe character  isNot found.**5.Char*STRSTR (Const Char*haystack,Const Char*needle); Locate a substringreturna pointer to the beginning of the substring, or NULLifThe substring isNot found.**6.Char*STRCASESTR (Const Char*haystack,Const Char*needle); Locate a Substring,ignores thereturna pointer to the beginning of the substring, Caseof both arguments. or NULLifThe substring isNot found.*

• Memory and string copy, Comparison function collation

*Function Name Purpose Note**1.void*memcpy (void*dest,Const void*src, size_t N); Copy Memory area the memcpy () function returns a pointer to Dest.**2.Char*strcpy (Char*dest,Const Char*SRC); Copy astring                         returnA pointer to the destinationstringdest.**3.Char*strncpy (Char*dest,Const Char*SRC, size_t N); Copy astring                         returnA pointer to the destinationstringdest.**4.void*memmove (void*dest,Const void*src, size_t N); Copy memory area, may overlap returns a pointer to Dest.**5.intmemcmpConst void*S1,Const void*s2, size_t N); Compare memory areas Returns an integer less than, equal to, or greater than zeroifThe first n bytes of s1 isfound**6.intstrcmpConst Char*S1,Const Char*S2); Compare stringsreturnAn integer less than, equal to, or greater than zeroifS1 isFoundfound**7.intstrncmpConst Char*S1,Const Char*S2, size_t N); Compare strings up**8.intSTRCASECMP (Const Char*S1,Const Char*S2); Compare strings Ignoring Case up**9.intSTRNCASECMP (Const Char*S1,Const Char*s2, size_t N); Compare strings Ignoring Case up**Ten.Char*strdup (Const Char*s); Duplicate AstringReturns a pointer to aNew stringwhich isA duplicate of thestringS. Memory forTheNew string  isobtained with*

• function collation of memory or string joins, splits, lengths, etc.

*Function Name Purpose Note*1.Char*strcat (Char*dest,Const Char*SRC); CONCATENATE stringsreturnA pointer to the resultingstringdest**2.Char*strncat (Char*dest,Const Char*src, size_t N); up up**3.Char*strtok (Char*STR,Const Char*delim); Extract Tokens fromstrings The first call, str must not be empty and the second call to Str must be empty**4.Char*strtok_r (Char*STR,Const Char*delim,Char**saveptr); reentrant function, thread safety recommended Use this partition function, the specific discussion see http://blog.csdn.net/liuintermilan/article/details/6283705*

Above, is the first item of finishing induction. Next, the second string conversion is summarized.

Summarize and organize the common library functions of C language in Linux----memory and string control and operation