C language string operation function implementation, C language string Function

C language string operation function implementation, C language string Function

1. String inversion-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. Copy strings-strcpy

char *strcpy(char *strDest, const char *strStr){    assert((NULL != strDest) && (NULL != strStr));    char *Dest=strDest;    while((*Dest++)=(*strStr++))    {}    return strDest;}

 

3. String concatenation-strcat

char *strcat(char *strDest, const char *strStr){    assert((NULL != strDest) && (NULL != strStr));    int length=strlen(strDest);    char *Dest=strDest+length;    while((*Dest++)=(*strStr++))    {}    return strDest;}

 

4. String comparison-strcmp

int strcmp(const 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(const char *strStr){    assert(NULL != strStr);    int length = 0;    while('\0' != *strStr)    {        length++;        strStr++;    }    return length;}

 

6. Convert string to number-atoi

int atoi(const char *strStr){    assert(NULL != strStr);    int minus = 0;    int begin = 0;    int sum = 0;    while('\0' !=*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*10 + (*strStr-'0');        }        strStr++;    }    return minus ? (-sum):(sum);}

 

7. convert numbers to strings-atoi

char *itoa(int num){    int temp,i,j;    char array[10];    static char strDest[10];    for(temp = num,i=0; i<10 && temp ;i++)    {        array[i]=temp%10+'0';        temp/=10;    }    for(i=i-1,j=0 ; i>=0 && j<10; i--,j++)    {        strDest[j]=array[i];    }    strDest[j]='\0';    return strDest;}

 

8. Calculate the number of metainfo characters in a string.

#include<stdio.h>#include<stdlib.h>#include<assert.h>#include<ctype.h>int isVowel(char letter){    switch(toupper(letter))    {        case 'A':        case 'E':        case 'I':        case 'O':        case 'U':            return 1;        default:            return 0;    }}int countVowel(const char * strStr){    assert(NULL != strStr);    int count=0;    while('\0' !=*strStr++)    {        if(isVowel(*strStr))            count++;    }    return count;}int main(){    char a[10]="hwlulr";    printf("%d\n",countVowel(a));    return 0;}

 

9. Determine whether a string is a return object.

# Include <stdio. h> # include <stdlib. h> # include <string. h> # include <assert. h> # include <ctype. h> int isEqual (char a, char B) {if (a = B) return 1; return 0;} int isPalindrome (const char * strStr) {assert (NULL! = StrStr); int length = strlen (strStr); int I, j; for (I = 0, j = length-1; I <j; I ++, j --) {/* Skip spaces and symbols */while (''= * (strStr + I) |! Isalpha (* (strStr + I) I ++; while (''= * (strStr + j) |! Isalpha (* (strStr + j) j --; if (0 = isEqual (* (strStr + I), * (strStr + j) return 0 ;} return 1;} int main () {char a [10] = "heo o, e h"; printf ("% s \ n", isPalindrome ()? "Is Palindrome": "is not Palindrome"); return 0 ;}