Question

我需要将ascii输入转换为十六进制输入。我对C非常不好，所以如果你能提供一些非常有帮助的解释。这段代码只是一堆零碎，但大多数可能是错误或无用的。之后我需要使用用户输入来选择字符串，但困难的部分是让它完全转换。

#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>

void crypt(char *buf, char *keybuf, int keylen) {
    //This is meant to encrypt by xor-ing with the sentence and key entered//
    //It is also supposed to replace the original buf with the new version post-xor//
    int i;
    int *xp;
    xp=&i;
    for(i=0; i<keylen; i++) {
    buf[i]=buf[i]^keybuf[i];
    xp++;
    }
}
int convertkey(char *keybuf) {
    int keylen=0;
    //I need to add something that will return the length of the key by incrementing keylen according to *keybuf//
    return keylen;
}
int main(int argc, char * argv[]){
    char x;
    char *xp;
    xp = &x;
    char a[47];
    char *ap;
    ap=a;
    printf("Enter Sentence: ");
    scanf("%[^\n]",a);
    printf("Enter key: ");
    scanf("%d",xp);
    printf("You entered the sentence: %s\n",a);
    printf("You entered the key: %d\n",x);

    convertkey(xp);
    crypt(ap,xp,x);
    printf("New Sentence: %s\n",a);
    return 0;
}

Answer 1

就是这样，我已经重新组织了你发布的代码，所以至少它会编译，即使意图不明确。也许你可以从这里接受它。

#include <stdio.h>
#include <stdlib.h>

// moved out of main()
void crypt(char *buf, char *keybuf, int keylen) { 
    int i;                          // added declaration
    for(i=0; i<keylen; i++) {       // corrected syntax and end condition
        buf[i]=buf[i]^keybuf[i];    
        //xp++;                     // out of scope
    }   
}

// moved out of main()
int convertkey(char *keybuf) {
    int keylen=0;
    return keylen;  
}

int main(int argc, char * argv[]){
    int x=0;
    int *xp;
    xp = &x;                        // xp=&x{0};
    return 0;                       // exit(0);
}

Answer 2

这是我正在寻找的最终产品，但在解释/编码时非常差。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void crypt(char *buf, char *keybuf, int keylen) {
    int i;
    int length= strlen(buf)-1;
    for(i=0; i<length; i++) {
    buf[i]=buf[i]^keybuf[i%keylen];
    printf("%c",buf[i]);
    }
    printf("\n");
}

int convertkey(char *keybuf) {
    int i=0;
    for(i=0;keybuf[i]!='\n';i++){
        if(keybuf[i]>='0' & keybuf[i]<='9'){
            keybuf[i]=keybuf[i]-'0';
        }
        else if(keybuf[i]>='a' & keybuf[i]<='f'){
            keybuf[i]=(keybuf[i]-'a')+10;
        }
    }
    return i;
}   

int main(int argc, char * argv[]){
    char keychars[12];
    char a[48];
    char *ap;
    int i;
    ap=a;
    printf("Enter Sentence: ");
    fgets(a, 48, stdin);
    printf("Enter Key: ");
    fgets(keychars, 12, stdin);
    for (i=0; i<strlen(keychars); i++) {
        char c = keychars[i];
        printf("keychars[%d]=%c (character), %d (decimal), %x (hex)\n", i, c, c, c);
    }
    crypt(ap,keychars,convertkey(keychars));
    return 0;
}

C ascii到十六进制代码

2 个答案: