[文件操作]替换文件中的字符串

文件操作函数：

int fseek(FILE *stream, long offset, int origin);

stream为文件指针

offset表示偏移量，正数表示正向偏移，负数表示负向偏移

origin文件从哪个位置开始偏移，可取值为SEEK_CUR, SEEK_END, SEEK_SET, 分别代表当前位置、文件结尾、文件开头。

long ftell(FILE *stream);

当前文件位置指针相对于文件头的偏移字节数，使用fseek函数后，再调用ftell可以精确获取文件当前位置

size_t fread(void *buffer, size_t size, size_t count, FILE *stream);

从文件流中读取数据count个项，每个项为size个字节，成功则返回读取到项的个数(<=count)，不成功或者读到文件末尾则返回0

fwrite
fputs/fputc/fputchar
fopen
fclose

 1 // BambooStrReplace.cpp : Defines the entry point for the console application.
 2 //
 3 
 4 #include <stdio.h>
 5 #include <stdlib.h>
 6 #include <string.h>
 7 
 8 #define BUFFER_SIZE    2048            //4096=4k
 9 
10 char *path = "C:\...\Makefile";
11 
12 const char *referStr = "ld_ar.mk";
13 
14 char srcStr[BUFFER_SIZE];
15 char dstStr[BUFFER_SIZE];
16 
17 int main()
18 {
19     FILE *fp;
20     int ret;
21 
22     // open file
23     fp = fopen(path, "rb+");
24     if (fp == NULL)
25     {
26         printf("file open failed
");
27         return 0;
28     }
29     // goto file end
30     fseek(fp, 0, SEEK_END);
31     // back to 1kbytes
32     if (ftell(fp) > BUFFER_SIZE)
33     {
34         fseek(fp, -BUFFER_SIZE, SEEK_CUR);
35     }
36     else
37     {
38         fseek(fp, -ftell(fp), SEEK_CUR);
39     }
40     int filePosition = ftell(fp);
41     //  clear str
42     memset(srcStr, 0, sizeof(srcStr));
43     memset(dstStr, 0, sizeof(srcStr));
44 
45     // read file to array
46     ret = fread(srcStr, 1, BUFFER_SIZE, fp);
47     memcpy(dstStr, srcStr, ret);
48     // get ld_ar.mk position
49     char * dstPosition = strstr(srcStr, referStr);
50     int SecondOffset = (int)dstPosition - (int)srcStr;
51     // get " position
52     while (*dstPosition != '"')
53     {
54         dstPosition--;
55     }
56     int fisrtOffset = (int)dstPosition - (int)srcStr;
57     int deleteLen = SecondOffset - fisrtOffset;
58 
59     dstStr[fisrtOffset + 1] = '.';                        // add "."
60     dstStr[fisrtOffset + 2] = '\';                        
61 
62     // delete string                                                                                                                
63     for (int i = fisrtOffset; i < ret - deleteLen; i++)
64     {
65         dstStr[i+3] = srcStr[i + deleteLen];
66     }
67     for (int i = ret - deleteLen; i < ret; i++)
68     {
69         dstStr[i] = '';
70     }
71     // put into Makefile
72     fseek(fp, filePosition, SEEK_SET);
73     fputs(dstStr, fp);
74     fclose(fp);
75     //system("pause");
76     return 0;
77 }