== 在比较 argv[] 字符串 [duplicate] 时不起作用

问：

我注意到使用 strcmp 和 == 运算符将普通字符串变量与字符串进行比较都有效，但使用 == 比较 argv 字符串不起作用，只有它适用于 strcmp。为什么？有什么特别之处？

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

int main(int argc, char const *argv[]) {
    char *tempStr = "string";
    int x = atoi(argv[2]), y = atoi(argv[3]);
    
    if (strcmp(tempStr, "string") == 0) {
        printf("'strcmp' methods works in case comparing with normal string variable\n");
    }
    if (tempStr == "string") {
        printf("'strcmp' as well as '==', both the methods works in case comparing with normal string variable\n");
    }
    

    /* this works for argv[] strings*/
    if (strcmp(argv[1], "add") == 0) printf("%d", x + y);
    else if (strcmp(argv[1], "subtract") == 0) printf("%d", x - y);
    else if (strcmp(argv[1], "multiply") == 0) printf("%d", x * y);
    else if (strcmp(argv[1], "divide") == 0) printf("%d", x / y);
    
    // /* this doesn't works for argv[] strings */ 
    // if (argv[1] == "add") printf("%d", x + y);
    // else if (argv[1] == "subtract") printf("%d", x - y);
    // else if (argv[1] == "multiply") printf("%d", x * y);
    // else if (argv[1] == "divide") printf("%d", x / y);

    return 0;
}