如果聲明流程連續如下

Question

if (srcbloc == NULL) { 
    fprintf(stderr, "warning!: memrip source is null!\n"); 
    exit(1); 
} 
if (destbloc == NULL) { 
    destbloc = malloc(len); 
} 
if (srcbloc == destbloc) { 
    fprintf(stderr, "warning!: srcbloc = destbloc\n"); 
    exit(1); 
} 
if (offset < 0) { 
    fprintf(stderr, "warning!: offset = %i\n", offset); 
} 
if (len < 0) { 
    fprintf(stderr, "warning!: len = %i\n", len); 
} 

我想知道是否所有的if語句都會在這個程序運行時被測試嗎？

Answer 1

鑑於你的代碼

if (srcbloc == NULL) { /* <-- if this block is entered then, */ 
    fprintf(stderr, "warning!: memrip source is null!\n"); 
    exit(1); /* <-- Program will exit */ 
} 
if (destbloc == NULL) { /* <-- Allocate destbloc of len length. */ 
    destbloc = malloc(len); 
} 
if (srcbloc == destbloc) { /* <-- if this block is entered then, */ 
    fprintf(stderr, "warning!: srcbloc = destbloc\n"); 
    exit(1); /* <-- Program will exit */ 
} 
if (offset < 0) { 
    fprintf(stderr, "warning!: offset = %i\n", offset); 
} 
if (len < 0) { 
    fprintf(stderr, "warning!: len = %i\n", len); 
} 

所以，如果(srcbloc == NULL)或(srcbloc == destbloc)程序會警告（退出）。如果其他測試中的任何一個匹配，將會打印警告，但該程序將繼續處理。