C-Language string manipulation function implementation

1. String reversal –strrev

void strrev (char *str) {    assert (NULL! = str);

    int length=strlen (str);     Char *end=str+length-1;      while (End > str)    {        *str= (*str) ^ (*end);         *end= (*STR) ^ (*end);         *str= (*STR) ^ (*end);        End--;        Str+ +;    }}

2. String Copy –strcpy

Char *strcpy (charconstChar *strStr) {    ! = strdest) && (NULL!) = strStr));     Char *dest=strdest;      while ((*dest++) = (*strstr++))    {}    return  strdest;}

3, String splicing –strcat

Char *strcat (charconstChar *strStr) {    ! = strdest) && (NULL!) = strStr));     int length=strlen (strdest);     Char *dest=strdest+length;      while ((*dest++) = (*strstr++))    {}    return  strdest;}

4. String comparison –strcmp

intstrcmpConst Char*strdest,Const Char*strStr) {Assert (NULL! = strdest) && (NULL! =strStr));  while(0= = (*strdest-*strstr) && *strdest) {strdest++; StrStr++; }    if(*strdest > *strStr)return 1; Else if(*strdest < *strStr)return-1; Else        return 0;}

5. String length –strlen

int strlen (constChar *strStr) {    ! = strStr)    ; int 0 ;      while ('strStr' ! = * * * *)    {        length+ +;        StrStr++    ;    } return length;}

6. String to Digital –atoi

intAtoiConst Char*strStr) {Assert (NULL!=strStr); intminus =0; intBegin =0; intsum =0;  while(' /'!=*strStr) {        if(0==begin && (isdigit (*strstr) | |'+'==*strstr | |'-'==*strStr)) {Begin=1; if('-'==*strStr) {Minus=1; StrStr++; Continue; }        }        Else if(!isdigit (*strStr)) {printf ("format is wrong!\n"); Exit (1); }        if(1==begin) {Sum= sum*Ten+ (*strstr-'0'); } strStr++; }    returnMinus? (-sum):(sum);}

7, Digital to string –atoi

Char*itoa (intnum) {    inttemp,i,j; Chararray[Ten]; Static Charstrdest[Ten];  for(temp = num,i=0; i<Ten&& temp; i++) {Array[i]=temp%Ten+'0'; Temp/=Ten; }     for(i=i-1, j=0; i>=0&& j<Ten; I--, J + +) {Strdest[j]=Array[i]; } Strdest[j]=' /'; returnstrdest;}

8. Count the number of vowel characters in a string

#include <stdio.h>#include<stdlib.h>#include<assert.h>#include<ctype.h>intIsvowel (CharLetter ) {    Switch(ToUpper (letter)) { Case 'A':         Case 'E':         Case 'I':         Case 'O':         Case 'U':            return 1; default:            return 0; }}intCountvowel (Const Char*strStr) {Assert (NULL!=strStr); intCount=0;  while(' /'!=*strstr++)    {        if(Isvowel (*strStr)) Count++; }    returncount;}intMain () {Chara[Ten]="HWLULR"; printf ("%d\n", Countvowel (a)); return 0;}

9, judge whether a string is a palindrome

#include <stdio.h>#include<stdlib.h>#include<string.h>#include<assert.h>#include<ctype.h>intTestCharACharb) {    if(a==b)return 1; return 0;}intIspalindrome (Const Char*strStr) {Assert (NULL!=strStr); intLength=strlen (STRSTR); inti,j;  for(i=0, j=length-1; I<j; i++,j--)    {        if(0==test (* (Strstr+i), * (strstr+J )))return 0; }    return 1;}intMain () {Chara[Ten]="Heooeh"; printf ("%s\n", Ispalindrome (a)?"is palindrome":"is not palindrome"); return 0;}

C-Language string manipulation function implementation