設置uint32關鍵位置並將其寫入文件時遇到問題

Question

我當前正試圖創建一個文件編碼器，它將幾行文本寫入.dat文件，並在運行可執行文件後輸出文件。但是，有一些錯誤使我無法編譯，我也不知道如何設置uint32keylocation。

這裏是我的代碼

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <stdint.h> 
/* 

message pair structure 
uint32 size 
char * message 

file spec: 
char * Header = CS2060 with no null byte 
uint32 keylocation 
messagePair First Name 
messagePair Last Name 
messagePair Message 1 = what grade you think you should get in class 
messagePair key 
messagePair message 2 = go for lol points 

    No code needed for assignment, just send the output file (.dat or .bin is an  appropriate file name extension) 

*/ 

int xor(char * in, uint32_t insize, char * pass, uint32_t passSize){ 
uint32_t i; 
for(i = 0; i < insize; i++){ 
    in[i] = in[i]^pass[i%passSize]; 
} 
return i; 
} 


int main(int argc, char ** argv){ 

if(argc != 2){ 
    fprintf(stderr,"Usage: %s [filename]\n",argv[0]); 
    return 1; 
} 
FILE * fh = fopen(argv[1],"rb"); 
if(!(fh)){ 
    fprintf(stderr,"Could not open file\n"); 
    return 1; 
} 

char header[7]; 
uint32_t keyloc; 
uint32_t fsize; 
uint32_t lsize; 
uint32_t keysize; 
uint32_t m1size; 
uint32_t m2size; 
uint32_t realLocation; 

char * first; 
char * last; 
char * key; 
char * m1; 
char * m2; 

fwrite(header, 6, 1, fh); 

if(strncmp(header,"CS2060",6)){ 
    fprintf(stderr,"header is incorrect\n"); 
    return 2; 
} 


fread(&keyloc,sizeof(uint32_t),1,fh); 
char first[] = 'name'; 
uint32_t fsize = strlen(first); 
fwrite(&fsize,sizeof(uint32_t),1,fh); 
fwrite(first,fsize,1,fh); 

fread(&keyloc,sizeof(uint32_t),1,fh); 
char last[] = 'namee'; 
uint32_t fsize = strlen(last); 
fwrite(&fsize,sizeof(uint32_t),1,fh); 
fwrite(last,fsize,1,fh); 

fread(&keyloc,sizeof(uint32_t),1,fh); 
char m1[] = 'B'; 
uint32_t fsize = strlen(m1); 
fwrite(&fsize,sizeof(uint32_t),1,fh); 
fwrite(m1,fsize,1,fh); 

fread(&keyloc,sizeof(uint32_t),1,fh); 
char key[] = 'The key is H'; 
uint32_t fsize = strlen(key); 
fwrite(&fsize,sizeof(uint32_t),1,fh); 
fwrite(key,fsize,1,fh); 

fread(&keyloc,sizeof(uint32_t),1,fh); 
char m2[] = 'https://www.youtube.com/watch?v=dQw4w9WgXcQ&ab_channel=RickAstleyVEVO'; 
uint32_t fsize = strlen(m2); 
fwrite(&fsize,sizeof(uint32_t),1,fh); 
fwrite(m2,fsize,1,fh); 

realLocation = ftell(fh); 
fread(&keysize,sizeof(uint32_t),1,fh); 
key = (char *)malloc(keysize+1); 
fread(key,keysize,1,fh); 
key[keysize] = 'H'; 


printf("First: %s\n",first); 
printf("Last: %s\n",last); 
printf("m1: %s\n",m1); 
printf("m2: %s\n",m2); 

if(realLocation == keyloc){ 
    printf("The location is correct\n"); 
}else{ 
    printf("The location is INCORRECT\n"); 
} 









return 0; 
} 

這裏是顯示錯誤消息，這是相當長的，我在哪裏開始的損失。

new2.c: In function ‘main’: 
new2.c:69:8: error: conflicting types for ‘first’ 
char *first[] = 'name'; 
    ^
new2.c:54:9: note: previous declaration of ‘first’ was here 
char * first; 
    ^
new2.c:69:18: warning: character constant too long for its type 
char *first[] = 'name'; 
      ^
new2.c:69:2: error: invalid initializer 
char *first[] = 'name'; 
^ 
new2.c:70:11: error: redeclaration of ‘fsize’ with no linkage 
uint32_t fsize = strlen(first); 
    ^
new2.c:47:11: note: previous declaration of ‘fsize’ was here 
uint32_t fsize; 
    ^
new2.c:70:26: warning: passing argument 1 of ‘strlen’ from incompatible pointer type 
uint32_t fsize = strlen(first); 
        ^
In file included from /usr/include/stdio.h:29:0, 
      from new2.c:1: 
/usr/include/string.h:33:9: note: expected ‘const char *’ but argument is of  type ‘char **’ 
size_t _EXFUN(strlen,(const char *)); 

這是我收到的每個寫入塊的錯誤。編輯2：好吧，所以在從頭開始重新構建之後，這就是我迄今爲止成功編寫的內容。所以我想我可以繼續使用這種格式來寫剩下的內容。我唯一的問題是什麼是uint32 keylocation，我該如何設置它？說明似乎含糊不清。還有我怎麼直接回複評論，但仍然包括我的代碼

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <stdint.h> 
/* 

message pair structure 
uint32 size 
char * message 

file spec: 
char * Header = CS2060 with no null byte 
uint32 keylocation 
messagePair First Name 
messagePair Last Name 
messagePair Message 1 = what grade you think you should get in class 
messagePair key 
messagePair message 2 = go for lol points 

No code needed for assignment, just send the output file (.dat or .bin is an appropriate file name extension) 

*/ 

int xor(char * in, uint32_t insize, char * pass, uint32_t passSize){ 
uint32_t i; 
for(i = 0; i < insize; i++){ 
    in[i] = in[i]^pass[i%passSize]; 
} 
return i; 
} 

int main(){ 

FILE * fp; 

fp = fopen("HW06.dat","w"); 
if(fp == NULL){ 
    printf("Could not open file\n"); 
    return 1; 
} 

char header[7] = "CS2060"; 
uint32_t keyloc; 
uint32_t fsize; 
uint32_t lsize; 
uint32_t keysize; 
uint32_t m1size; 
uint32_t m2size; 
uint32_t realLocation; 

char * first; 
char * last; 
char * key; 
char * m1; 
char * m2; 


fwrite(header,sizeof(char), 6, fp); 


fclose(fp); 
return 0; 
} 

Answer 1

一個問題是在錯誤消息中顯示得很好，我認爲，這是重新聲明。

例如，考慮這一點，

char * first; 

您已經聲明first是指向一個char，但在下面一行

char first[] = 'name'; 

聲明它是一個數組。這稱爲重新聲明（顯示在您的錯誤消息中）。即使重新聲明char*也會被拒絕，除非重新聲明它爲新類型（char數組）。

編輯：另外，上面的聲明是錯誤的，因爲單引號'a'用於聲明單個字符。要聲明一個字符串（或C中的char數組），請使用雙引號"name"。

你似乎也多次宣佈fsize（同一問題）。

要使用/分配已經宣佈fsize，簡單地說fsize=something而不是uint32_t fsize=something

的原則是，一旦你聲明一個變量，你只需要使用它 - 從來沒有重新申報。

例如，

int a = 67, b = 10; //declared 
a = a + b; //use 

而且不

int a = 67, b = 10; //declared 
int a = a + b; //re-declaration!!!!