Question

我已经看到了有关指针和整数比较问题的各种解释，但是我对此仍然很困惑。自从我开始编码以来，我一直在为指针而苦恼，这似乎是我似乎无法掌握的。而且我发现自己经常遇到类似的问题。我获得了以下“警告”信号，我认为每种信号的解决方案都相似。谁能帮忙深入解释这个常见的指针问题？

错误

scanner.c: In function ‘delimiters’:
scanner.c:14:9: warning: comparison between pointer and integer [enabled by default]
if(ch == delimiter[i])
     ^
scanner.c: In function ‘operators’:
scanner.c:27:9: warning: comparison between pointer and integer [enabled by default]
 if(ch == operator[i]){
     ^
scanner.c: In function ‘validIdentifier’:
scanner.c:43:2: warning: passing argument 1 of ‘delimiters’ makes pointer from integer without a cast [enabled by default]
if(id[0] == '0' || id[0] == '1' || id[0] == '2' || id[0] == '3' || id[0] == '4' || id[0] == '5' || id[0] == '6' || id[0] == '7' || id[0] == '8' || id[0] == '9' || delimiters(id[0]) == true || isupper(id[0]) )
                                                                            ^
scanner.c:8:6: note: expected ‘char *’ but argument is of type ‘char’
bool delimiters(char *ch){
  ^
scanner.c: In function ‘keywords’:
scanner.c:51:2: warning: passing argument 2 of ‘strcmp’ from incompatible pointer type [enabled by default]
 if(!strcmp(ch, keyword)){
 ^
In file included from scanner.c:3:0:
/usr/include/string.h:140:12: note: expected ‘const char *’ but argument is of type ‘const char **’
extern int strcmp (const char *__s1, const char *__s2)

code.c

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include "token.h"

bool delimiters(char *ch){
    int i, j;
    int len = strlen(ch);
    const char delimiter[10];

    for(i = 0; i < len; i++){
            if(ch == delimiter[i])
                    j = true;;
            j = false;
    }
    return (j);
}

bool operators(char *ch){
    int i, j;
    int len = strlen(ch);
    const char operator[10];

    for(i = 0; i < len; i++){
            if(ch == operator[i]){
                    j = true;
            }
            j = false;
    }
    return (j);
}

bool validIdentifier(char* id){
    int len = strlen(id);

    if((len == 0) || (len > 8)){
            printf("Invalid identifier (string) length\n");
            return (false);
    }

    if(id[0] == '0' || id[0] == '1' || id[0] == '2' || id[0] == '3' || id[0] == '4' || id[0] == '5' || id[0] == '6' || id[0] == '7' || id[0] == '8' || id[0] == '9' || delimiters(id[0]) == true || isupper(id[0]) )
            return (false);
    return (true);
}

bool keywords(char* ch){
    const char* keyword[12];

    if(!strcmp(ch, keyword)){
            return (true);
    }
    return (false);
}

bool isInteger(char* ch){
    int i;
    int len = strlen(ch);

    if((len == 0) || (len > 8)){
            printf("Invalid number length\n");
            return (false);
    }

    for(i = 0; i < len; i++){
            if((ch[i] != '0' && ch[i] != '1' && ch[i] != '2' && ch[i] != '3' && ch[i] != '4' && ch[i] != '5' && ch[i] != '6' && ch[i] != '7' && ch[i] != '8' && ch[i] != '9' && ch[i] != '.') || (ch[i] == '-' && i > 0)){
                    return (false);
            }
    }
    return (true);
}

char* sub(char* str, int l, int r){
    int i;
    char* subString = (char*)malloc(sizeof(char) * (r - l + 2));

    for(i = l; i < r; i++){
            subString[i - l] = str[i];
    }

    subString[r - l + 1] = '\0';
    return (subString);
}

指针和整数错误之间的比较

0 个答案: