[英]gcc warning: braces around scalar initializer
我有如下定義的查找表,我正在使用GCC。 當我編譯時,我收到警告
warning: braces around scalar initializer
這個警告意味着什么? 我該如何初始化這個LUT? 我在初始化這個結構時犯了錯誤嗎?
救命!!
typedef struct TECH
{
float velocity1, velocity2;
float temp;
float measure;
int id;
float storage[64];
}TECH;
struct TECH lut_model_1[2] = {{{296.001465},
{74.216972},
{2.025908},
{1.516384},
{1},
{0.001746,
0.000256, 0.006216, 0.005249, -0.001668, -0.001377, 0.009865, 0.010454, -0.000288, -0.005853, 0.010584, 0.015440, 0.000465, -0.000602, 0.004330, 0.005700, 0.017120,
0.233015, 0.034154, 0.244022, 0.007644, 0.385683, 0.042960, 0.406633, -0.007811, 0.346931, 0.040123, 0.387361, 0.007030, 0.225309, 0.017897, 0.241024, 0.003700,
0.103601, 0.060748, 0.121059, -0.045041, 0.076974, 0.070647, 0.148810, -0.022399, 0.074007, 0.054797, 0.141794, 0.010376, 0.052482, 0.045013, 0.078443, -0.019940,
-0.057353, 0.044285, 0.066622, -0.058232, -0.093817, 0.064753, 0.126611, -0.008286, -0.085634, 0.029582, 0.140443, 0.009189, -0.052974, 0.036057, 0.087536}},
{{309.270569},
{74.520226},
{2.088673},
{1.595730},
{1},
{-0.003261,
0.001452, 0.006673, 0.007092, 0.001020, 0.002904, 0.009037, 0.009587, -0.001494, 0.000296, 0.009327, 0.010013, -0.000301, -0.002727, 0.005875, 0.008888, -0.016850,
0.231185, 0.029758, 0.241629, 0.009411, 0.382748, 0.057553, 0.407984, -0.019496, 0.393691, 0.045355, 0.411033, -0.019787, 0.185746, 0.027101, 0.216863, 0.010189,
0.050463, 0.041380, 0.059462, 0.009747, 0.093188, 0.089831, 0.132579, -0.049612, 0.058789, 0.075130, 0.122026, -0.022185, 0.017041, 0.035450, 0.074255, -0.002068,
-0.061219, 0.040752, 0.087084, -0.013021, -0.106098, 0.066566, 0.140099, -0.041966, -0.073433, 0.055231, 0.125908, -0.003481, -0.050690, 0.017257, 0.085251}}};
您應該刪除大括號: {
和}
圍繞單個值。
struct TECH lut_model_1[2] = {{296.001465,
74.216972,
2.025908,
1.516384,
1,
{0.001746,
0.000256, 0.006216, 0.005249, -0.001668, -0.001377, 0.009865, 0.010454, -0.000288, -0.005853, 0.010584, 0.015440, 0.000465, -0.000602, 0.004330, 0.005700, 0.017120,
0.233015, 0.034154, 0.244022, 0.007644, 0.385683, 0.042960, 0.406633, -0.007811, 0.346931, 0.040123, 0.387361, 0.007030, 0.225309, 0.017897, 0.241024, 0.003700,
0.103601, 0.060748, 0.121059, -0.045041, 0.076974, 0.070647, 0.148810, -0.022399, 0.074007, 0.054797, 0.141794, 0.010376, 0.052482, 0.045013, 0.078443, -0.019940,
-0.057353, 0.044285, 0.066622, -0.058232, -0.093817, 0.064753, 0.126611, -0.008286, -0.085634, 0.029582, 0.140443, 0.009189, -0.052974, 0.036057, 0.087536}},
{309.270569,
74.520226,
2.088673,
1.595730,
1,
{-0.003261,
0.001452, 0.006673, 0.007092, 0.001020, 0.002904, 0.009037, 0.009587, -0.001494, 0.000296, 0.009327, 0.010013, -0.000301, -0.002727, 0.005875, 0.008888, -0.016850,
0.231185, 0.029758, 0.241629, 0.009411, 0.382748, 0.057553, 0.407984, -0.019496, 0.393691, 0.045355, 0.411033, -0.019787, 0.185746, 0.027101, 0.216863, 0.010189,
0.050463, 0.041380, 0.059462, 0.009747, 0.093188, 0.089831, 0.132579, -0.049612, 0.058789, 0.075130, 0.122026, -0.022185, 0.017041, 0.035450, 0.074255, -0.002068,
-0.061219, 0.040752, 0.087084, -0.013021, -0.106098, 0.066566, 0.140099, -0.041966, -0.073433, 0.055231, 0.125908, -0.003481, -0.050690, 0.017257, 0.085251}}};
不會發出警告。
在C語言中,在初始化標量值時使用額外的大括號是完全合法的,如
int x = { 5 };
即使您通常不會在現實代碼中看到這一點。 在你的情況下,你做的是同樣的事情,除了你的情況下標量值是一個更大的聚合的成員。
GCC為這樣的代碼生成警告。 它認為你有可能寫了一些你不打算寫的東西,因為大多數時候大括號都是用來為聚合啟動多部分初始化器,而不是標量的獨立初始化器。
<rant>
GCC肯定會對聚合初始值設定項中有關括號的警告搞砸了。 在C語言中, { 0 }
一直被用作慣用的通用零初始化器。 對於其慣用值,至少{ 0 }
應該免除與大括號相關的警告。 </rant>
這是一個標量初始化器: int foo = 3;
這是一個帶有大括號的標量初始化器: int foo = {3};
這是數組的初始值設定項,它不是標量: int foo[] = {1, 2, 3};
警告說你的struct有標量初始值設定項,並帶有括號:
typedef struct TECH
{
float velocity1, velocity2;
...
struct TECH lut_model_1[2] = {{{296.001465},
{74.216972},
...
你的代碼可以工作,它只是在它的標量初始化器周圍有多余的括號。 如果你把括號拿出來並將其格式化得更好(我將第一個初始化器放在它自己的行上),那就不會有任何令人反感的了。
這意味着您無需在以下位置放置大括號:
{74.216972},
基本上,你在那里的所有括號都是可選的(除了外部的),但是,你會得到一個不同的警告,因為它不包含初始化器中的嵌套結構。 基本上,如果你介意警告,只在嵌套的結構和數組周圍加上大括號; 如果沒有,請使用它們來提高您的可讀性。
您可以通過用大括號括起標量值(velocity1,temp等)來初始化標量值,這是不需要的。
嘗試這個:
struct TECH lut_model_1[2] = {{296.001465,
74.216972,
2.025908,
1.516384,
1,
{0.001746,
0.000256, 0.006216, 0.005249, -0.001668, -0.001377, 0.009865, 0.010454, -0.000288, -0.005853, 0.010584, 0.015440, 0.000465, -0.000602, 0.004330, 0.005700, 0.017120,
0.233015, 0.034154, 0.244022, 0.007644, 0.385683, 0.042960, 0.406633, -0.007811, 0.346931, 0.040123, 0.387361, 0.007030, 0.225309, 0.017897, 0.241024, 0.003700,
0.103601, 0.060748, 0.121059, -0.045041, 0.076974, 0.070647, 0.148810, -0.022399, 0.074007, 0.054797, 0.141794, 0.010376, 0.052482, 0.045013, 0.078443, -0.019940,
-0.057353, 0.044285, 0.066622, -0.058232, -0.093817, 0.064753, 0.126611, -0.008286, -0.085634, 0.029582, 0.140443, 0.009189, -0.052974, 0.036057, 0.087536}},
{309.270569,
74.520226,
2.088673,
1.595730,
1,
{-0.003261,
0.001452, 0.006673, 0.007092, 0.001020, 0.002904, 0.009037, 0.009587, -0.001494, 0.000296, 0.009327, 0.010013, -0.000301, -0.002727, 0.005875, 0.008888, -0.016850,
0.231185, 0.029758, 0.241629, 0.009411, 0.382748, 0.057553, 0.407984, -0.019496, 0.393691, 0.045355, 0.411033, -0.019787, 0.185746, 0.027101, 0.216863, 0.010189,
0.050463, 0.041380, 0.059462, 0.009747, 0.093188, 0.089831, 0.132579, -0.049612, 0.058789, 0.075130, 0.122026, -0.022185, 0.017041, 0.035450, 0.074255, -0.002068,
-0.061219, 0.040752, 0.087084, -0.013021, -0.106098, 0.066566, 0.140099, -0.041966, -0.073433, 0.055231, 0.125908, -0.003481, -0.050690, 0.017257, 0.085251}}};
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