c/c++ 修改文本文件内容、替换字符串函数(linux、mac下)Windows版会陆续发布

#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include<string.h>
#include<stdio.h>
#include <unistd.h>
#include <sys/stat.h>

//求子串
char* substr(const char*str, unsigned long start, unsigned long end);

void replace(const char *ori, const char *dst, int fd, unsigned char *buffer, unsigned long size);

//替换文本. ori:将要替换的字符串、dst:替换的目的字符串, path:文件名
void replace(const char *ori, const char *dst, const char *path);

int main(int argc, char** argv) // map a normal file as shared mem:
{
    replace("#", "*", "/Users/zctech/Desktop/test.cpp");
}


//求子串
char* substr(const char*str, unsigned long start, unsigned long end)
{
    unsigned long n = end - start;
    static char stbuf[1024 * 512];
    strncpy(stbuf, str + start, n);
    stbuf[n] = 0;                           //字串最后加上0
    return stbuf;
}


void replace(const char *ori, const char *dst, int fd, unsigned char *buffer, unsigned long size)
{
    unsigned char *buf = new unsigned char[size];
    unsigned long i = 0;
    
    unsigned long *dSize = new unsigned long;
    *dSize = size;  //动态文件大小，由于替换数据造成文件加大
    
    unsigned char *buffer2 = new unsigned char[size];
    memccpy(buffer2, buffer, sizeof(unsigned char), size);
    
    while (i < *dSize)
    {
        if(0 == strcmp(ori, substr((char *)buffer2, i, i + strlen(ori))))
        {
            //定位到#号+1位置读取数据
            lseek(fd, i + 1, SEEK_SET);
            read(fd, buf, *dSize - i - 1);
            
            
            //定位到#号+1+length的位置
            lseek(fd, i + strlen(dst), SEEK_SET);
            write(fd, buf, *dSize - i - 1);
            
            
            //回到#号位置并写入数据
            lseek(fd, i, SEEK_SET);
            write(fd, dst, strlen(dst));
            
            //由于size变了,需要修改dSize,将数据存储在临时指针中
            unsigned char *t = buffer2;
            
            *dSize += strlen(dst) - 1;
            buffer2 = new unsigned char[*dSize];
            lseek(fd, 0, SEEK_SET);
            read(fd, buffer2, *dSize);
            
            delete []t;
        }
        i++;
    }
    delete dSize;
}


//删除注释.path:文件名
void replace(const char *ori, const char *dst, const char *path)
{
    
    int fd = open(path, O_RDWR);
    
    //获取文件大小
    struct stat sb;
    fstat(fd, &sb);
    
    unsigned char *start = (unsigned char *)mmap(NULL, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
    if(start == MAP_FAILED) /* 判断是否映射成功 */
    {
        printf("映射失败，文件过大或者没有权限");
        return;
    }
    
    replace(ori, dst, fd, start, sb.st_size);
    
    close(fd);
    munmap(start, sb.st_size); /* 解除映射 */
    
}